Document:

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                                                                     EXHIBIT 4.3

                                EXCHANGE SECURITY

CUSIP No. 538021AM8

                THIS SECURITY IS A GLOBAL SECURITY WITHIN THE MEANING OF THE
INDENTURE HEREINAFTER REFERRED TO AND IS REGISTERED IN THE NAME OF A DEPOSITARY
OR A NOMINEE THEREOF. THIS SECURITY MAY NOT BE EXCHANGED IN WHOLE OR IN PART FOR
A SECURITY REGISTERED, AND NO TRANSFER OF THIS SECURITY IN WHOLE OR IN PART MAY
BE REGISTERED, IN THE NAME OF ANY PERSON OTHER THAN SUCH DEPOSITARY OR A NOMINEE
THEREOF, EXCEPT IN THE LIMITED CIRCUMSTANCES DESCRIBED HEREIN OR IN THE
INDENTURE.

                UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED
REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY, A NEW YORK CORPORATION ("DTC"),
TO LITTON INDUSTRIES, INC. OR ITS AGENT FOR REGISTRATION OF TRANSFER, EXCHANGE,
OR PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE NAME OF CEDE & CO.
OR IN SUCH OTHER NAME AS IS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF DTC
(AND ANY PAYMENT IS MADE TO CEDE & CO. OR TO SUCH OTHER ENTITY AS IS REQUESTED
BY AN AUTHORIZED REPRESENTATIVE OF DTC), ANY TRANSFER, PLEDGE, OR OTHER USE
HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL INASMUCH AS THE
REGISTERED OWNER HEREOF, CEDE & CO., HAS AN INTEREST HEREIN.

                             LITTON INDUSTRIES, INC.

                            8% Senior Notes due 2009

No. R-1                                                        $400,000,000

                LITTON INDUSTRIES, INC., a corporation duly organized and
existing under the laws of the State of Delaware (herein called the "Company",
which term includes any successor Person under the Indenture hereinafter
referred to), for value received, hereby promises to pay to CEDE & CO., or
registered assigns, the principal sum of Four Hundred Million Dollars on October
15, 2009, and to pay interest thereon from October 18, 1999 or from the most
recent Interest Payment Date to which interest has been paid or duly provided
for, semi-annually on April 15 and October 15 in each year, commencing April 15,
2000, at the rate of 8% per annum, until the principal hereof is paid or made
available for payment. The interest so payable, and punctually paid or duly
provided for, on any Interest

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Payment Date will, as provided in such Indenture, be paid to the Person in whose
name this Security (or one or more Predecessor Securities) is registered at the
close of business on the Regular Record Date for such interest, which shall be
the April 1 or October 1 (whether or not a Business Day), as the case may be,
next preceding such Interest Payment Date. Any such interest not so punctually
paid or duly provided for will forthwith cease to be payable to the Holder on
such Regular Record Date and may either be paid to the Person in whose name this
Security (or one or more Predecessor Securities) is registered at the close of
business on a Special Record Date for the payment of such Defaulted Interest to
be fixed by the Trustee, notice whereof shall be mailed to Holders of Securities
of this series not less than 10 days prior to such Special Record Date, or be
paid at any time in any other lawful manner not inconsistent with the
requirements of any securities exchange on which the Securities of this series
may be listed, and upon such notice as may be required by such exchange, all as
more fully provided in said Indenture. Interest on the Securities of each series
shall be computed on the basis of a 360-day year of twelve 30-day months.

                Payment of the principal of (and premium, if any) and any such
interest on this Security will be made at the office or agency of the Company
maintained for that purpose in The Borough of Manhattan, The City of New York,
in such coin or currency of the United States of America as at the time of
payment is legal tender for payment of public and private debts; provided,
however, that at the option of the Company payment of interest may be made by
check mailed to the address of the Person entitled thereto as such address shall
appear in the Security Register.

                Reference is hereby made to the further provisions of this
Security set forth on the reverse hereof, which further provisions shall for all
purposes have the same effect as if set forth at this place.

                Unless the certificate of authentication hereon has been
executed by the Trustee referred to on the reverse hereof by manual signature,
this Security shall not be entitled to any benefit under the Indenture or be
valid or obligatory for any purpose.

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                IN WITNESS WHEREOF, the Company has caused this instrument to be
duly executed.

                                        LITTON INDUSTRIES, INC.

                                        By   Timothy G. Paulson
                                             Vice President and Treasurer

Attest:

Lynne M.O. Brickner
Secretary

CERTIFICATE OF AUTHENTICATION

This is one of the Securities of the series designated therein referred to in
the within-mentioned Indenture.

Dated:

                                        THE BANK OF NEW YORK,
                                                 As Trustee

                                        By   JoAnn Manieri
                                             Authorized Signatory

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                              [REVERSE OF SECURITY]

                This Security is one of a duly authorized issue of securities of
the Company (herein called the "Securities"), issued and to be issued in one or
more series under an Indenture, dated as of April 13, 1998 (herein called the
"Indenture", which term shall have the meaning assigned to it in such
instrument), between the Company and The Bank of New York, as Trustee (herein
called the "Trustee", which term includes any successor trustee under the
Indenture), and reference is hereby made to the Indenture for a statement of the
respective rights, limitations of rights, duties and immunities thereunder of
the Company, the Trustee and the Holders of the Securities and of the terms upon
which the Securities are, and are to be, authenticated and delivered. This
Security is one of the series designated on the face hereof, initially limited
in aggregate principal amount to $400,000,000, subject to certain exceptions
referred to in the Indenture. In addition, the Company may from time to time
without the consent of the Holders of Securities create and issue further
securities having the same terms and conditions as the Securities in all
respects (or in all respects except for the issue date and issue price) and so
that such further issue shall be consolidated and form a single series with the
outstanding securities of this series (including the Securities) or upon such
terms as the Company may determine at the time of their issue. References herein
to the Securities include (unless the context requires otherwise) any other
securities issued as described in this paragraph and forming a single series
with the Securities.

                The Securities of this series are subject to redemption upon not
less than 30 days' notice by mail, in whole or in part, at the option of the
Company at any time at a Redemption Price equal to the greater of (i) 100% of
the principal amount of the Securities so redeemed or (ii) as determined by a
Quotation Agent, the sum of the present values of the remaining scheduled
payments of principal and interest thereon (not including any portion of such
payments of interest accrued as of the date of redemption) discounted to the
redemption date on a semiannual basis (assuming a 360-day year consisting of
twelve 30-day months) at the Adjusted Treasury Rate, plus 15 basis points plus,
in each case, accrued interest thereon to the Redemption Date.

                  "Adjusted Treasury Rate" means, with respect to any Redemption
Date, the rate per annum equal to the

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semiannual equivalent yield to maturity of the Comparable Treasury Issue,
assuming a price for the Comparable Treasury Issue (expressed as a percentage of
its principal amount) equal to the Comparable Treasury Price for such Redemption
Date.

                "Comparable Treasury Issue" means the United States Treasury
security selected by a Quotation Agent as having a maturity comparable to the
remaining term of the Securities to be redeemed that would be utilized, at the
time of selection and in accordance with customary financial practice, in
pricing new issues of corporate debt securities of comparable maturity to the
remaining term of such Securities.

                "Comparable Treasury Issue" means, with respect to any
redemption date, (i) the average of the Reference Treasury Dealer Quotations for
that redemption date, after excluding the highest and lowest of the Reference
Treasury Dealer Quotations, or (ii) if the Trustee obtains fewer than three such
Reference Treasury Dealer Quotations, the average of all Reference Treasury
Dealer Quotations so received.

                "Quotation Agent" means the Reference Treasury Dealer appointed
by the Company.

                "Reference Treasury Dealer" means (i) each of J.P. Morgan
Securities Inc., Credit Suisse First Boston Corporation, Banc of America
Securities LLC, BNY Capital Markets, Inc., Chase Securities Inc. and Salomon
Smith Barney Inc. and their respective successors unless any of them ceases to
be a primary U.S. Government securities dealer in New York City (a "Primary
Treasury Dealer"), in which case the Company shall substitute another Primary
Treasury Dealer, and (ii) any other Primary Treasury dealer selected by the
Company.

                "Reference Treasury Dealer Quotations" means, with respect to
each Reference Treasury Dealer and any redemption date, the average, as
determined by the Company, of the bid and asked prices for Comparable Treasury
Issue (expressed in each case as a percentage of its principal amount) quoted in
writing to the Trustee by that Reference Treasury dealer at 5:00 p.m., New York
City time, on the third business day preceding that redemption date.

                  In the event of redemption of this Security in part only, a
new Security or Securities of this series and of like tenor for the unredeemed
portion hereof will be

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issued in the name of the Holder hereof upon the cancellation hereof.

                This Security shall have the benefit of the covenants and
agreements set forth herein and in the Indenture, subject to the limited
exceptions referred to in the Officers' Certificate of the Company creating the
Securities of this series (the "Officers' Certificate"). The Company shall not,
and shall not permit any Subsidiary (as defined below) to, create, assume or
suffer to exist any mortgage, pledge, lien, encumbrance, charge or security
interest (collectively, a "Lien") upon Restricted Property (as defined below) to
secure any debt of the Company, any Subsidiary or any other Person (as defined
below), without making effective provision whereby the Notes then outstanding
shall be secured by the Lien equally and ratably with such debt for so long as
such debt shall be so secured, except that the foregoing shall not prevent the
Company or any Subsidiary from creating, assuming or suffering to exist Liens of
the following character: (1) any Lien existing on the date of issuance of the
Notes; (2) any Lien existing on property owned or leased by a corporation at the
time it becomes a Subsidiary; (3) any Lien existing on property at the time of
the acquisition thereof by the Company or a Subsidiary; (4) any Lien to secure
any debt incurred prior to, at the time of, or within 12 months after the
acquisition of Restricted Property for the purpose of financing all or any part
of the purchase price thereof and any Lien to the extent that it secures debt
which is in excess of such purchase price and for the payment of which recourse
may be had only against such Restricted Property; (5) any Lien to secure any
debt incurred prior to, at the time of, or within 12 months after the completion
of the construction or commencement of commercial operation, alteration, repair
or improvement of Restricted Property for the purpose of financing all or any
part of the cost thereof and any Lien to the extent that it secures debt which
is in excess of such cost and for the payment of which recourse may be had only
against such Restricted Property; (6) any Lien securing debt of a Subsidiary
owing to the Company or to another Subsidiary; (7) any Lien in favor of the
United States of America or any State thereof or any other country, or any
agency, instrumentality or political subdivision of any of the foregoing, to
secure partial, progress, advance or other payments or performance pursuant to
the provisions of any contract or statute, or any Liens securing industrial
development, pollution control, or similar revenue bonds; (8) any extension,
renewal or replacement (or successive

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extensions, renewals or replacements) in whole or in part of any Lien referred
to in clauses (1) through (7) above, so long as the principal amount of debt so
secured at the time of the extension, renewal or replacement (except that, where
an additional principal amount of debt is incurred to provide funds for the
completion of a specific project, the additional principal amount, and any
related financing costs, may be secured by the Lien as well) and the Lien is
limited to the same property subject to the Lien so extended, renewed or
replaced (plus improvements on the property); and (9) any Lien not permitted by
clauses (1) through (8) above securing debt which, together with the aggregate
outstanding principal amount of all other debt of the Company and its
Subsidiaries owning Restricted Property which would otherwise be subject to the
foregoing restrictions and the aggregate Value (as defined below) of existing
Sale and Leaseback Transactions (as defined below) which would be subject to the
restrictions herein but for this clause (9), does not at any time exceed 15% of
Consolidated Net Tangible Assets (as defined below).

                The Company shall not enter into any Sale and Leaseback
Transaction, nor permit any Subsidiary owning Restricted Property so to do,
unless either (1) the Company or such Subsidiary would be entitled to incur
debt, in a principal amount at least equal to the Value of such Sale and
Leaseback Transaction, which is secured by Liens on the property to be leased
(without equally and ratably securing the outstanding Securities) because such
Liens would be of such character that no violation of any of the provisions
herein would result or (2) the Company during the six months immediately
following the effective date of such Sale and Leaseback Transaction causes to be
applied to (A) the acquisition of Restricted Property or (B) the voluntary
retirement of Funded Debt (as defined below) (whether by redemption, defeasance,
repurchase or otherwise) an amount equal to the Value of such Sale and Leaseback
Transaction.

                "Consolidated Net Tangible Assets" means the total amount of
assets (less applicable reserves and other properly deductible items) after
deducting (1) all current liabilities (excluding the amount of those which are
by their terms extendable or renewable at the option of the obligor to a date
more than 12 months after the date as of which the amount is being determined)
and (2) all goodwill, tradenames, trademarks, patents, unamortized debt discount
and expense and other like intangible assets, all as set forth on the most
recent balance sheet of the Company and

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its consolidated subsidiaries and determined in accordance with generally
accepted accounting principals.

                "Funded Debt" means indebtedness of the Company or a Subsidiary
owning Restricted Property maturing by its terms more than one year after its
creation and indebtedness classified as long-term debt under generally accepted
accounting principles and in each case ranking at least pari passu with the
Securities.

                "Restricted Property" means (1) any manufacturing facility, or
portion thereof, owned or leased by the Company or any Subsidiary and located
within the continental United States of America, which, in the opinion of the
Board of Directors, is of material importance to the business of the Company and
its Subsidiaries taken as a whole, but no such manufacturing facility, or
portion thereof, shall be deemed of material importance if its gross book value
(before deducting accumulated depreciation) is less than 2% of Consolidated Net
Tangible Assets, or (2) any shares of capital stock or indebtedness of any
Subsidiary owning any such manufacturing facility. As used in this definition,
"manufacturing facility" means property, plant and equipment used for actual
manufacturing such as quality assurance, engineering, maintenances, staging
areas for work in process materials, employees' eating and comfort facilities
and manufacturing administration, and it excludes sales offices, research
facilities and facilities used only for warehousing or general administration.

                "Sale and Leaseback Transaction" means any arrangement with any
individual, corporation, partnership, joint venture, association, joint-stock
company, trust, unincorporated organization or government or any agency or
political subdivision thereof ("Person") pursuant to which the Company or any
Subsidiary leases any Restricted Property that has been or is to be sold or
transferred by the Company or the subsidiary to such Person, other than (1)
temporary leases for a term, including renewals at the option of the lessee, of
not more than three years, (2) leases between the Company and a Subsidiary or
between Subsidiaries, (3) leases of a Restricted Property executed by the time
of, or within 12 months after the latest of, the acquisition, the completion of
construction or improvement, or the commencement of commercial operation of the
Restricted Property, and (4) arrangements pursuant to any provision of law with
an effect similar to the former Section 168(f)(8) of the Internal Revenue code
of 1954.

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                "Subsidiary" of any specified corporation, for purposes of the
covenants set forth herein, means (i) a corporation, a majority of whose shares,
interests, rights to purchase, warrants, options, participations or other
equivalents of or interests (however designated) in stock with voting power,
under ordinary circumstances, to elect directors is, at the date of
determination, directly or indirectly owned by the Company, by one or more
Subsidiaries of the Company or by the Company and one or more Subsidiaries of
the Company or (ii) a partnership in which the Company or a Subsidiary of the
Company is at the date of determination, a general partner of such partnership,
or (iii) any other Person (other than a corporation or a partnership) in which
the Company, a Subsidiary of the Company or the Company and one or more
Subsidiaries of the Company, directly or indirectly, at the date of
determination, has (x) at least a majority ownership interest or (y) the power
to elect or direct the election of a majority of the directors or other
governing body of such Person.

                "Value" means, with respect to a Sale and Leaseback Transaction,
an amount equal to the present value of the lease payments with respect to the
term of the lease remaining on the date as of which the amount is being
determined, without regard to any renewal or extension options contained in the
lease, discounted at the weighted average interest rate on the Securities of all
series (including the effective rate on any original issue discount Securities)
which are outstanding on the effective date of such Sale and Leaseback
Transaction and which have the benefit of the provisions herein.

                The Indenture and the Officers' Certificate contain provisions
for defeasance of the entire indebtedness of this Security or certain
restrictive covenants with respect to this Security, in each case upon
compliance with certain conditions set forth in the Indenture.

                If an Event of Default with respect to Securities of this series
shall occur and be continuing, the principal of the Securities of this series
may be declared due and payable in the manner and with the effect provided in
the Indenture. In addition, during the continuance of an Event of Default,
Holders of Securities will be entitled to request and receive individual
definitive Registered Securities.

                                        9
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                The Indenture permits, with certain exceptions as therein
provided, the amendment thereof and the modification of the rights and
obligations of the Company and the rights of the Holders of the Securities of
each series to be affected under the Indenture at any time by the Company and
the Trustee with the consent of the Holders of a majority in principal amount of
the Securities at the time Outstanding of each series to be affected. The
Indenture also contains provisions permitting the Holders of specified
percentages in principal amount of the Securities of each series at the time
Outstanding, on behalf of the Holders of all Securities of such series, to waive
compliance by the Company with certain provisions of the Indenture and certain
past defaults under the Indenture and their consequences. Any such consent or
waiver by the Holder of this Security shall be conclusive and binding upon such
Holder and upon all future Holders of this Security and of any Security issued
upon the transfer hereof or in exchange herefor or in lieu hereof, whether or
not notation of such consent or waiver is made upon this Security.

                As provided in and subject to the provisions of the Indenture,
the Holder of this Security shall not have the right to institute any proceeding
with respect to the Indenture or for the appointment of a receiver or trustee or
for any other remedy thereunder, unless such Holder shall have previously given
the Trustee written notice of a continuing Event of Default with respect to the
Securities of this series, the Holders of not less than 25% in principal amount
of the Securities of this series at the time Outstanding shall have made written
request to the Trustee to institute proceedings in respect of such Event of
Default as Trustee and offered the Trustee reasonable indemnity, and the Trustee
shall not have received from the Holders of a majority in principal amount of
Securities of this series at the time Outstanding a direction inconsistent with
such request, and shall have failed to institute any such proceeding, for 60
days after receipt of such notice, request and offer of indemnity. The foregoing
shall not apply to any suit instituted by the Holder of this Security for the
enforcement of any payment of principal hereof or any premium or interest hereon
on or after the respective due dates expressed herein.

                No reference herein to the Indenture and no provision of this
Security or of the Indenture shall alter or impair the obligation of the
Company, which is absolute

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and unconditional, to pay the principal of and any premium and interest on this
Security at the times, place and rate, and in the coin or currency, herein
prescribed.

                As provided in the Indenture and subject to certain limitations
therein set forth, the transfer of this Security is registrable in the Security
Register, upon surrender of this Security for transfer at the office or agency
of the Company in any place where the principal of and any premium and interest
on this Security are payable, duly endorsed by, or accompanied by a written
instrument of transfer in form satisfactory to the Company and the Security
Registrar duly executed by, the Holder hereof or his attorney duly authorized in
writing, and thereupon one or more new Securities of this series and of like
tenor, of authorized denominations and for the same aggregate principal amount,
will be issued to the designated transferee or transferees.

                The Securities of this series are issuable only in registered
form without coupons in denominations of $1,000 and any integral multiple
thereof. As provided in the Indenture and subject to certain limitations therein
set forth, Securities of this series are exchangeable for a like aggregate
principal amount of Securities of this series and of like tenor of a different
authorized denomination, as requested by the Holder surrendering the same.

                No service charge shall be made for any such transfer or
exchange, but the Company may require payment of a sum sufficient to cover any
tax or other governmental charge payable in connection therewith.

                Prior to due presentment of this Security for transfer, the
Company, the Trustee and any agent of the Company or the Trustee may treat the
Person in whose name this Security is registered as the owner hereof for all
purposes, whether or not this Security be overdue, and neither the Company, the
Trustee nor any such agent shall be affected by notice to the contrary.

                All terms used in this Security which are defined in the
Indenture shall have the meanings assigned to them in the Indenture.

                THIS INDENTURE AND THE SECURITIES SHALL BE GOVERNED BY AND
CONSTRUED IN ACCORDANCE WITH THE LAW OF THE STATE OF NEW YORK.

                                       11<PAGE>   1
                                                                     EXHIBIT 4.2

                                                                  Execution Copy

================================================================================

                                    COLO.COM,
                                    as Issuer

                                       and

                           STATE STREET BANK AND TRUST
                          COMPANY OF CALIFORNIA, N.A.,
                                   as Trustee

                             Senior Notes Indenture

                           Dated as of March 10, 2000

                               up to $400,000,000

                          13 7/8% Senior Notes due 2010

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                              CROSS-REFERENCE TABLE

<TABLE>
<CAPTION>
TIA Sections                                                      Indenture Sections
------------                                                      ------------------
<S>                                                               <C>
SECTION 310(a)(1).........................................             7.10
      (a)(5)..............................................             7.10
      (b).................................................             7.03; 7.08
SECTION 311...............................................             7.03
SECTION 313(a)............................................             7.06
      (c).................................................             7.05; 7.06
SECTION 314(a)............................................             4.17
      (b).................................................             10.01
      (c)(1)..............................................             1.01
      (d).................................................             10.01
      (e).................................................             1.01
SECTION 315(a)............................................             7.02
      (b).................................................             7.05; 10.02
SECTION 316(a)............................................             6.06
</TABLE>

Note:   The Cross-Reference Table shall not for any purpose be deemed to be a
        part of this Indenture.

<PAGE>   3

                                TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                                               Page
                                                                                               ----
<S>                                                                                            <C>
RECITALS OF THE COMPANY.....................................................................      1

             ARTICLE ONE DEFINITIONS AND INCORPORATION BY REFERENCE

SECTION 1.01.  Definitions..................................................................      2
SECTION 1.02.  Incorporation by Reference of Trust Indenture Act............................     23
SECTION 1.03.  Rules of Construction........................................................     23

                             ARTICLE TWO THE NOTES

SECTION 2.01.  Form and Dating..............................................................     24
SECTION 2.02.  Restrictive Legends..........................................................     25
SECTION 2.03.  Execution, Authentication and Denominations..................................     26
SECTION 2.04.  Registrar and Paying Agent...................................................     27
SECTION 2.05.  Paying Agent to Hold Money in Trust..........................................     28
SECTION 2.06.  Transfer and Exchange........................................................     28
SECTION 2.07.  Book-Entry Provisions for Global Notes.......................................     29
SECTION 2.08.  Special Transfer Provisions..................................................     31
SECTION 2.09.  Replacement Notes............................................................     33
SECTION 2.10.  Outstanding Notes............................................................     33
SECTION 2.11.  Temporary Notes..............................................................     34
SECTION 2.12.  Cancellation.................................................................     34
SECTION 2.13.  CUSIP Numbers................................................................     35
SECTION 2.14.  Defaulted Interest...........................................................     35
SECTION 2.15.  Issuance of Additional Notes.................................................     35

                            ARTICLE THREE REDEMPTION

SECTION 3.01.  Right of Redemption..........................................................     35
SECTION 3.02.  Notices to Trustee...........................................................     36
SECTION 3.03.  Selection of Notes to Be Redeemed............................................     36
SECTION 3.04.  Notice of Redemption.........................................................     36
SECTION 3.05.  Effect of Notice of Redemption...............................................     37
SECTION 3.06.  Deposit of Redemption Price..................................................     38
SECTION 3.07.  Payment of Notes Called for Redemption.......................................     38
SECTION 3.08.  Notes Redeemed in Part.......................................................     38

                             ARTICLE FOUR COVENANTS

SECTION 4.01.  Payment of Notes.............................................................     38
SECTION 4.02.  Maintenance of Office or Agency..............................................     39
SECTION 4.03.  Limitation on the Incurrence of Indebtedness and the Issuance of Preferred
               Stock........................................................................     40
</TABLE>

--------
Note:   The Table of Contents shall not for any purposes be deemed to be a part
        of this Indenture.

<PAGE>   4

<TABLE>
<S>                                                                                             <C>
SECTION 4.04.  Limitation on Restricted Payments............................................     44
SECTION 4.05.  Limitation on Dividend and Other Payment Restrictions Affecting Restricted
               Subsidiaries.................................................................     48
SECTION 4.06.  Limitation on the Issuance and Sale of Capital Stock of Restricted
               Subsidiaries.................................................................     50
SECTION 4.07.  Limitation on Issuances of Guarantees by Restricted Subsidiaries.............     51
SECTION 4.08.  Limitation on Transactions with Affiliates...................................     52
SECTION 4.09.  Limitation on Liens..........................................................     53
SECTION 4.10.  Limitation on Sale-Leaseback Transactions....................................     54
SECTION 4.11.  Limitation on Asset Sales....................................................     55
SECTION 4.12.  Repurchase of Notes upon a Change of Control.................................     56
SECTION 4.13.  Business Activities..........................................................     57
SECTION 4.14.  Existence....................................................................     57
SECTION 4.15.  Payment of Taxes and Other Claims............................................     57
SECTION 4.16.  Maintenance of Properties and Insurance......................................     57
SECTION 4.17.  Notice of Defaults...........................................................     58
SECTION 4.18.  Compliance Certificates......................................................     58
SECTION 4.19.  Commission Reports and Reports to Holders....................................     58
SECTION 4.20.  Waiver of Stay, Extension or Usury Laws......................................     59

                       ARTICLE FIVE SUCCESSOR CORPORATION

SECTION 5.01.  When Company May Merge, Etc..................................................     59
SECTION 5.02.  Successor Substituted........................................................     60

                        ARTICLE SIX DEFAULT AND REMEDIES

SECTION 6.01.  Events of Default............................................................     60
SECTION 6.02.  Acceleration.................................................................     62
SECTION 6.03.  Other Remedies...............................................................     63
SECTION 6.04.  Waiver of Past Defaults......................................................     63
SECTION 6.05.  Control by Majority..........................................................     63
SECTION 6.06.  Limitation on Suits..........................................................     63
SECTION 6.07.  Rights of Holders to Receive Payment.........................................     64
SECTION 6.08.  Collection Suit by Trustee...................................................     64
SECTION 6.09.  Trustee May File Proofs of Claim.............................................     65
SECTION 6.10.  Priorities...................................................................     65
SECTION 6.11.  Undertaking for Costs........................................................     65
SECTION 6.12.  Restoration of Rights and Remedies...........................................     66
SECTION 6.13.  Rights and Remedies Cumulative...............................................     66
SECTION 6.14.  Delay or Omission Not Waiver.................................................     66

                             ARTICLE SEVEN TRUSTEE

SECTION 7.01.  General......................................................................     66
SECTION 7.02.  Certain Rights of Trustee....................................................     67
SECTION 7.03.  Individual Rights of Trustee.................................................     68
</TABLE>

<PAGE>   5
<TABLE>
<S>                                                                                            <C>
SECTION 7.04.  Trustee's Disclaimer.........................................................     68
SECTION 7.05.  Notice of Default............................................................     68
SECTION 7.06.  Reports by Trustee to Holders................................................     69
SECTION 7.07.  Compensation and Indemnity...................................................     69
SECTION 7.08.  Replacement of Trustee.......................................................     70
SECTION 7.09.  Successor Trustee by Merger, Etc.............................................     71
SECTION 7.10.  Eligibility..................................................................     71
SECTION 7.11.  Money Held in Trust..........................................................     71
SECTION 7.12.  Withholding Taxes............................................................     71

                      ARTICLE EIGHT DISCHARGE OF INDENTURE

SECTION 8.01.  Termination of the Company's Obligations.....................................     71
SECTION 8.02.  Defeasance and Discharge of Indenture........................................     72
SECTION 8.03.  Defeasance of Certain Obligations............................................     74
SECTION 8.04.  Application of Trust Money...................................................     74
SECTION 8.05.  Repayment to Company.........................................................     75
SECTION 8.06.  Reinstatement................................................................     75
SECTION 8.07.  Defeasance and Certain Other Events of Default...............................     75

                ARTICLE NINE AMENDMENTS, SUPPLEMENTS AND WAIVERS

SECTION 9.01.  Without Consent of Holders...................................................     76
SECTION 9.02.  With Consent of Holders......................................................     76
SECTION 9.03.  Revocation and Effect of Consent.............................................     77
SECTION 9.04.  Notation on or Exchange of Notes.............................................     78
SECTION 9.05.  Trustee to Sign Amendments, Etc..............................................     78
SECTION 9.06.  Conformity with Trust Indenture Act..........................................     78

                              ARTICLE TEN SECURITY

SECTION 10.01.  Security....................................................................     79

                          ARTICLE ELEVEN MISCELLANEOUS

SECTION 11.01.  Trust Indenture Act of 1939.................................................     80
SECTION 11.02.  Notices.....................................................................     80
SECTION 11.03.  Certificate and Opinion as to Conditions Precedent..........................     82
SECTION 11.04.  Statements Required in Certificate or Opinion...............................     82
SECTION 11.05.  Rules by Trustee, Paying Agent or Registrar.................................     83
SECTION 11.06.  Payment Date Other Than a Business Day......................................     83
SECTION 11.07.  Governing Law; Submission to Jurisdiction; Agent for Service................     83
SECTION 11.08.  No Adverse Interpretation of Other Agreements...............................     83
SECTION 11.09.  No Recourse Against Others..................................................     83
SECTION 11.10.  Successors..................................................................     84
SECTION 11.11.  Duplicate Originals.........................................................     84
SECTION 11.12.  Separability................................................................     84
SECTION 11.13.  Table of Contents, Headings, Etc............................................     84
</TABLE>

<PAGE>   6

<TABLE>
<CAPTION>
                                                                                               Page
                                                                                               ----
<S>                                                                                            <C>
EXHIBIT A      Form of Global Note.........................................................     A-1
EXHIBIT B      Form of Certificated Note...................................................     B-1
EXHIBIT C      Form of Certificate to Be Delivered in Connection with
               Transfers to Non-QIB Accredited Investors...................................     C-1
</TABLE>

<PAGE>   7

             INDENTURE, dated as of March 19, 1999, between COLO.COM, a
California corporation, as issuer (the "Company"), and STATE STREET BANK AND
TRUST COMPANY OF CALIFORNIA, N.A., a national banking association, as trustee
(the "Trustee").

                             RECITALS OF THE COMPANY

             The Company has duly authorized the execution and delivery of this
Indenture to provide for the issuance from time to time of 13 7/8% Senior Notes
due 2010 (the "Notes") issuable as provided in this Indenture. Pursuant to the
terms of a Purchase Agreement dated as of March 3, 2000 (the "Purchase
Agreement") between the Company and Goldman, Sachs & Co., as the manager for
itself and the several initial purchasers named on Schedule I thereto, the
Company has agreed to issue and sell an aggregate of 300,000 Units (the
"Units"), each of which consists of a Note with a principal amount of $1,000 and
one warrant (each a "Warrant"), each Warrant entitling the holder thereof to
purchase 19.9718 shares of Common Stock, par value $0.01 per share, of the
Company. The Notes and Warrants included in each Unit will become separately
transferable upon the earliest to occur of (i) the date that is one year
following the Closing Date, (ii) 180 days after the closing of the date of the
Company's initial public offering (iii) the commencement of the Exchange Offer
pursuant to the Registration Rights Agreement, (iv) the date the Shelf
Registration Statement (as defined herein) is declared effective, (v) the
commencement of an Offer to Purchase (as defined herein) the Notes upon a Change
of Control (as defined herein) or (vi) such date as determined by Goldman, Sachs
& Co. in its sole discretion (the "Separation Date").

             All things necessary to make this Indenture a valid agreement of
the Company, in accordance with its terms, have been done, and the Company has
done all things necessary to make the Notes, when executed by the Company and
authenticated and delivered by the Trustee hereunder and duly issued by the
Company, the legal, valid and binding obligations of the Company as hereinafter
provided.

             This Indenture will, upon the effectiveness of the registration
statement provided for under the Registration Rights Agreement, be subject to,
and governed by, the provisions of the Trust Indenture Act of 1939, as amended,
that are required to be a part of and to govern indentures qualified under the
Trust Indenture Act of 1939, as amended.

             For and in consideration of the premises and the purchase of the
Notes by the Holders thereof, it is mutually covenanted and agreed, for the
equal and proportionate benefit of all Holders, as follows.

                                   ARTICLE ONE
                   DEFINITIONS AND INCORPORATION BY REFERENCE

<PAGE>   8
                                       2

             SECTION 1.01. Definitions.

             "Acquired Indebtedness" or "Acquired Preferred Stock" means, with
respect to any specified Person, Indebtedness or Preferred stock of any other
Person existing at the time such other Person is merged with or into or becomes
a Restricted Subsidiary of such specified Person or assumed in connection with
an Asset Acquisition by such specified Person; provided that such Indebtedness
or Preferred Stock is not incurred in connection with, or in contemplation of,
such other Person merging with or into or becoming a Subsidiary of such
specified Person; provided that such Indebtedness or Preferred Stock of such
other Person which is redeemed, defeased, retired or otherwise repaid at the
time of or immediately upon consummation of the transactions by which such
Person becomes a Restricted Subsidiary or such Asset Acquisition shall not be
Acquired Indebtedness or Acquired Preferred Stock.

             "Adjusted Consolidated Net Income" means, for any period, the
aggregate net income (or loss) of the Company and its Restricted Subsidiaries
for such period, on a consolidated basis, determined in conformity with GAAP;
provided that the following items shall be excluded in computing Adjusted
Consolidated Net Income (without duplication): (i) the net income (or loss) of
any Person that is not a Restricted Subsidiary, except (x) with respect to net
income, to the extent of the amount of dividends or other distributions actually
paid to the Company or any of its Restricted Subsidiaries by such Person during
such period and (y) with respect to net losses, to the extent of the amount of
Investments made by the Company or any Restricted Subsidiary in such Person
during such period; (ii) the net income (or loss) of any Person accrued prior to
the date it becomes a Restricted Subsidiary or is merged into or consolidated
with the Company or any of its Restricted Subsidiaries or all or substantially
all of the property and assets of such Person are acquired by the Company or any
of its Restricted Subsidiaries; (iii) the net income of any Restricted
Subsidiary to the extent that the declaration or payment of dividends or similar
distributions by such Restricted Subsidiary of such net income is not at the
time permitted by the operation of the terms of its charter or any agreement,
instrument, judgment, decree, order, statute, rule or governmental regulation
applicable to such Restricted Subsidiary; (iv) any gains or losses (on an
after-tax basis) attributable to sales of assets outside the ordinary course of
business of the Company and its Restricted Subsidiaries; (v) solely for purposes
of calculating the amount of Restricted Payments that may be made pursuant to
clause (C) of the first paragraph of Section 4.04 hereof, any amount paid or
accrued as dividends on Preferred Stock of the Company or any Restricted
Subsidiary owned by Persons other than the Company and any of its Restricted
Subsidiaries; and (vi) all extraordinary gains and, solely for the purpose of
calculating the Consolidated Leverage Ratio, extraordinary losses.

             "Affiliate" means, as applied to any specified Person, any other
Person directly or indirectly controlling, controlled by, or under direct or
indirect common control with, such specified Person. For purposes of this
definition, "control" (including, with correlative

<PAGE>   9
                                       3

meanings, the terms "controlling," "controlled by" and "under common control
with"), as applied to any Person, means the possession, directly or indirectly,
of the power to direct or cause the direction of the management and policies of
such Person, whether through the ownership of voting securities, by contract or
otherwise; provided that beneficial ownership of less than 10% of the Voting
Stock of a Person shall be deemed not to be control.

             "Agent" means any Registrar, Paying Agent, authenticating agent or
co-Registrar.

             "Agent Members" has the meaning provided in Section 2.07(a) hereof.

             "Asset Acquisition" means (i) an investment by the Company or any
of its Restricted Subsidiaries in any other Person pursuant to which such Person
shall become a Restricted Subsidiary or shall be merged into or consolidated
with the Company or any of its Restricted Subsidiaries; provided that such
Person is engaged in a Permitted Business or (ii) an acquisition by the Company
or any of its Restricted Subsidiaries of the property and assets of any Person
other than the Company or any of its Restricted Subsidiaries that constitute
substantially all of a division or line of business of such Person; provided
that the property and assets acquired are related, ancillary or complementary to
a Permitted Business.

             "Asset Disposition" means the sale or other disposition by the
Company or any of its Restricted Subsidiaries (other than to the Company or
another Restricted Subsidiary) of (i) all or substantially all of the Capital
Stock of any Restricted Subsidiary or (ii) all or substantially all of the
assets that constitute a division or line of business of the Company or any of
its Restricted Subsidiaries.

             "Asset Sale" means any sale, transfer or other disposition
(including by way of merger, consolidation or sale-leaseback transaction) in one
transaction or a series of related transactions by the Company or any of its
Restricted Subsidiaries to any Person other than the Company or any of its
Restricted Subsidiaries of (i) all or any of the Capital Stock of any
Subsidiary, (ii) all or substantially all of the property and assets of an
operating unit or business of the Company or any of its Restricted Subsidiaries
or (iii) any other property and assets (other than the Capital Stock or other
Investment in an Unrestricted Subsidiary) of the Company or any of its
Restricted Subsidiaries outside the ordinary course of business of the Company
or such Restricted Subsidiary and, in each case, that is not governed by Article
Five hereof; provided that "Asset Sale" shall not include (a) sales or other
dispositions of inventory, receivables and related assets and other current
assets, (b) sales, transfers or other dispositions constituting the making or
liquidating of a Permitted Investment or a Restricted Payment permitted to be
made under Section 4.04 hereof, (c) sales, transfers or other dispositions of
assets with a fair market value (as certified in an Officers' Certificate) not
in excess of $1.0 million in any transaction or series of related transactions,
(d) any sale , transfer, assignment or other disposition of any property or
equipment that has become damaged, worn out, obsolete or otherwise unsuitable
for use in

<PAGE>   10
                                       4

connection with the business of the Company or its Restricted Subsidiaries, (e)
sales, transfers, assignments or other dispositions constituting the granting of
Liens otherwise permitted by this Indenture, (f) sales, transfers or assignments
of all or substantially all of the assets of the Company or mergers or
consolidations in compliance with Section 4.11, (g) sales, transfers or other
dispositions in the ordinary course of business of such Person, or (h) the
licensing by the Company or any Restricted Subsidiary of intellectual property.

             "Average Life" means, at any date of determination with respect to
any debt security, the quotient obtained by dividing (i) the sum of the products
of (a) the number of years from such date of determination to the dates of each
successive scheduled principal payment of such debt security and (b) the amount
of such principal payment by (ii) the sum of all such principal payments.

             "Board of Directors" means the Board of Directors of the Company as
required by the context or any committee of such Board of Directors duly
authorized to act under this Indenture.

             "Board Resolution" means a copy of a resolution, certified by the
Secretary or Assistant Secretary of the Company as required by the context to
have been duly adopted by the Board of Directors and to be in full force and
effect on the date of such certification, and delivered to the Trustee.

             "Business Day" means any day except a Saturday, Sunday or other day
on which commercial banks in the City of New York, in the city of the Corporate
Trust Office of the Trustee or in the city in which any Paying Agent or
Registrar is located are authorized or required by law to close.

             "Capital Stock" means, with respect to any Person, any and all
shares, interests, participations or other equivalents (however designated,
whether voting or non-voting) in equity of such Person, whether outstanding on
the Closing Date or issued thereafter, including, without limitation, all Common
Stock and Preferred Stock; provided that the term "Capital Stock" shall not
include any Indebtedness Convertible into Capital Stock of such Person.

             "Capitalized Lease" means, as applied to any Person, any lease of
any property (whether real, personal or mixed) of which the discounted present
value of the rental obligations of such Person as lessee, in conformity with
GAAP, is required to be capitalized on the balance sheet of such Person.

             "Capitalized Lease Obligations" means the capitalized portion of a
Capitalized Lease in accordance with GAAP.

<PAGE>   11
                                       5

             "Certificated Notes" has the meaning provided in Section 2.01
hereof.

             "Change of Control" means such time as (i) (a) prior to the
occurrence of a Public Market, a "person" or "group" (within the meaning of
Sections 13(d) and 14(d)(2) of the Exchange Act), other than an Existing
Stockholder, becomes the ultimate "beneficial owner" (as defined in Rule 13d-3
under the Exchange Act) of Voting Stock representing a greater percentage of the
total voting power of the Voting Stock of the Company, on a fully diluted basis,
than is held by the Existing Stockholders on such date and (b) on or after the
occurrence of a Public Market, a "person" or "group" (within the meaning of
Sections 13(d) and 14(d)(2) of the Exchange Act), other than an Existing
Stockholder, becomes the ultimate "beneficial owner" (as defined in Rule 13d-3
under the Exchange Act) of more than 50% of the total voting power of the Voting
Stock of the Company on a fully diluted basis or (ii) individuals who on the
Closing Date constitute the Board of Directors (together with any new directors
whose election by the Board of Directors or whose nomination by the Board of
Directors for election by the Company's stockholders was approved by a vote of
at least a majority of the members of the Board of Directors then in office who
either were members of the Board of Directors on the Closing Date or whose
election or nomination for election was previously so approved) cease for any
reason to constitute a majority of the members of the Board of Directors then in
office for a period of two years.

             "Closing Date" means the date on which the Notes are originally
issued under this Indenture.

             "Closing Price" on any Trading Day with respect to the per share
price of any shares of Capital Stock means the last reported sale price regular
way or, in case no such sale takes place on such day, the average of the
reported closing bid and asked prices regular way, in either case on the New
York Stock Exchange, or, if such shares of Capital Stock are not listed or
admitted to trading on such exchange, on the principal national securities
exchange on which such shares are listed or admitted to trading on any national
securities exchange, on the Nasdaq Stock Market, or if such shares are not
listed or admitted to trading or, if not listed or admitted to trading on any
national securities exchange or quoted on the Nasdaq Stock Market, the average
of the closing bid and asked prices in the over-the-counter market as furnished
by any New York Stock Exchange member firm of national standing that is selected
from time to time by the Company for that purpose.

             "Commission" means the Securities and Exchange Commission, as from
time to time constituted, created under the Exchange Act or, if at any time
after the execution of this instrument such Commission is not existing and
performing the duties now assigned to it under the TIA, then the body performing
such duties at such time.

<PAGE>   12
                                       6

             "Commodity Agreement" means any forward contract, commodity swap
agreement, commodity option agreement or other similar agreement or arrangement.

             "Common Stock" means, with respect to any Person, any and all
shares, interests, participations or other equivalents (however designated,
whether voting or non-voting) of such Person's common stock, whether now
outstanding or issued after the date of this Indenture, including, without
limitation, all series and classes of such common stock.

             "Company" means the party named as such in the first paragraph of
this Indenture until a successor replaces it pursuant to the applicable
provisions of this Indenture and thereafter means the successor.

             "Company Order" means a written request or order signed in the name
of the Company (i) by its Chairman of the Board, the Vice Chairman of the Board,
its President or a Vice President or (ii) by its Chief Financial Officer,
Treasurer, an Assistant Treasurer, its Secretary or an Assistant Secretary and
delivered to the Trustee.

             "Consolidated EBITDA" means, for any period, Adjusted Consolidated
Net Income for such period plus, to the extent such amount was deducted in
calculating such Adjusted Consolidated Net Income, (i) Consolidated Interest
Expense, (ii) income taxes, (iii) depreciation expense, (iv) amortization
expense and (v) all other non-cash items reducing Adjusted Consolidated Net
Income (other than items that will require cash payments and for which an
accrual or reserve is, or is required by GAAP to be, made), less all non-cash
items increasing Adjusted Consolidated Net Income, all as determined on a
consolidated basis for the Company and its Restricted Subsidiaries in conformity
with GAAP; provided that, if any Restricted Subsidiary is not a Wholly Owned
Restricted Subsidiary, Consolidated EBITDA shall be reduced (to the extent not
otherwise reduced in accordance with GAAP) by an amount equal to (A) the amount
of the Adjusted Consolidated Net Income attributable to such Restricted
Subsidiary multiplied by (B) the percentage ownership interest in the income of
such Restricted Subsidiary not owned on the last day of such period by the
Company or any of its Restricted Subsidiaries.

             "Consolidated Interest Expense" means, for any period, the
aggregate amount of interest in respect of Indebtedness (including, without
limitation, amortization of original issue discount on any Indebtedness and the
interest portion of any deferred payment obligation, calculated in accordance
with the effective interest method of accounting; all commissions, discounts and
other fees and charges owed with respect to letters of credit and bankers'
acceptance financing; the net costs associated with Interest Rate Agreements;
and Indebtedness that is Guaranteed or secured by the Company or any of its
Restricted Subsidiaries), one-third of the rental expense of all operating
leases of the Company and its Restricted Subsidiaries and all but the principal
component of rentals in respect of Capitalized Lease Obligations paid, accrued

<PAGE>   13
                                       7

or scheduled to be paid or to be accrued by the Company and its Restricted
Subsidiaries during such period; excluding, however, (1) any amount of such
interest of any Restricted Subsidiary if the net income of such Restricted
Subsidiary is excluded in the calculation of Adjusted Consolidated Net Income
pursuant to clause (iii) of the definition thereof (but only in the same
proportion as the net income of such Restricted Subsidiary is excluded from the
calculation of Adjusted Consolidated Net Income pursuant to clause (iii) of the
definition thereof) and (2) any premiums, fees and expenses (and any
amortization thereof) payable in connection with the offering of the Units, all
as determined on a consolidated basis (without taking into account Unrestricted
Subsidiaries) in conformity with GAAP.

             "Consolidated Leverage Ratio" means, with respect to the Company on
any Transaction Date, the ratio of (1) the aggregate amount of Indebtedness of
the Company and its Restricted Subsidiaries on a consolidated basis outstanding
on such Transaction Date to (2) four times Consolidated EBITDA for the most
recently ended fiscal quarter for which financial statements of the Company have
been filed with the Commission or provided to the Trustee pursuant to Section
4.18 hereof. Notwithstanding the definition of Adjusted Consolidated Net Income,
for the purposes of calculating the "Consolidated EBITDA" for any fiscal quarter
for purposes of this definition, (i) any Subsidiary of the Company that is a
Restricted Subsidiary on the Transaction Date shall be deemed to have been a
Restricted Subsidiary at all times during such fiscal quarter and (ii) any
Subsidiary of the Company that is not a Restricted Subsidiary on the Transaction
Date shall be deemed not to have been a Restricted Subsidiary at any time during
such fiscal quarter. In addition to and without limitation of the foregoing, for
purposes of this definition, "consolidated EBITDA" shall be calculated after
giving effect on a pro forma basis for the applicable fiscal quarter to, without
duplication: (A) the Incurrence or repayment of any Indebtedness to be Incurred
or repaid on the Transaction Date; (B) Asset Dispositions and Asset Acquisitions
(including giving pro forma effect to the application of proceeds of any Asset
Disposition) that occur from the beginning of the most recently ended fiscal
quarter, for which financial statements of the Company have been filed with the
SEC or provided to the Trustee pursuant to Section 4.19, through the Transaction
Date (the "Reference Period"), as if they had occurred and such proceeds had
been applied on the first day of such Reference Period; and (C) asset
dispositions and asset acquisitions (including giving pro forma effect to the
application of proceeds of any asset disposition) that have been made by any
Person that has become a Restricted Subsidiary or has been merged with or into
the Company or any Restricted Subsidiary during such Reference Period and that
would have constituted Asset Dispositions or Asset Acquisitions had such
transactions occurred when such Person was a Restricted Subsidiary as if such
asset dispositions or asset acquisitions were Asset Dispositions or Asset
Acquisitions that occurred on the first day of such Reference Period; provided
that to the extent that clause (B) or (C) of this sentence requires that pro
forma effect be given to an Asset Acquisition or Asset Disposition, such pro
forma calculation shall be based upon the full fiscal quarter immediately
preceding the Transaction Date of the Person, or division or line of business of
the Person, that is acquired or disposed of for which financial information is
available.

<PAGE>   14
                                       8

             "Convertible Notes" means notes that are convertible into Capital
Stock of the Company at the option of the holders thereof.

             "Credit Facility" means any credit facilities, any receivables
facilities or programs, or one or more other term loan and/or revolving credit
or commercial paper facilities (including any letter of credit subfacilities)
entered into with commercial banks or other financial institutions or
institutional investors, or any replacement, extension, renewal, refinancing or
refunding thereof.

             "Corporate Trust Office" means the office of the Trustee at which
the corporate trust business of the Trustee shall, at any particular time, be
principally administered, which office is, at the date of this Indenture,
located at 633 West 5th Street, 12th Floor, Los Angeles, CA 90071, Attention:
Corporate Trust Department.

             "Currency Agreement" means any foreign exchange contract, currency
swap agreement or other similar agreement or arrangement.

             "Default" means any event that is, or after notice or passage of
time or both would be, an Event of Default.

             "Depository" shall mean DTC.

             "Disqualified Stock" means any class or series of Capital Stock of
any Person that by its terms or otherwise is (i) required to be redeemed prior
to the Stated Maturity of the Notes, (ii) redeemable at the option of the holder
of such class or series of Capital Stock at any time prior to the Stated
Maturity of the Notes or (iii) convertible into or exchangeable for Capital
Stock referred to in clause (i) or (ii) above or Indebtedness having a scheduled
maturity prior to the Stated Maturity of the Notes; provided that any Capital
Stock that would not constitute Disqualified Stock but for provisions thereof
giving holders thereof (a) the right to require such Person to repurchase or
redeem such Capital Stock upon the occurrence of an "asset sale" or "change of
control" occurring prior to the Stated Maturity of the Notes shall not
constitute Disqualified Stock if the "asset sale" or "change of control"
provisions applicable to such Capital Stock are no more favorable to the holders
of such Capital Stock than the provisions contained in Sections 4.11 and 4.12
hereof, and such Capital Stock, or the agreements or instruments governing the
redemption rights thereof, specifically provides that such Person will not
repurchase or redeem any such stock pursuant to such provision prior to the
Company's repurchase of such Notes as are required to be repurchased pursuant to
Sections 4.11 and 4.12 hereof or (b) the right to require such Person to
repurchase in any other event, if such repurchase right is expressly contingent
on the payment in full of the Notes.

<PAGE>   15
                                       9

             "DTC" means The Depository Trust Company, its nominees, and their
respective successors.

             "Event of Default" has the meaning provided in Section 6.01 hereof.

             "Excess Proceeds" has the meaning provided in Section 4.11 hereof.

             "Exchange Act" means the Securities Exchange Act of 1934, as
amended.

             "Exchange Notes" means any notes of the Company containing terms
identical to the Notes (except that such Exchange Notes (i) shall be registered
under the Securities Act, (ii) will not provide for an increase in the rate of
interest (other than with respect to overdue amounts) and (iii) will not contain
terms with respect to transfer restrictions) that are issued and exchanged for
the Notes pursuant to the Registration Rights Agreement and this Indenture.

             "Existing Stockholders" means Accel Partners, Athena Venture Fund
L.P., Investcorp International, Menlo Ventures and Meritech Capital Partners,
and, in each case, affiliated funds.

             "Existing Vendor Finance Agreements" means, collectively, (i) the
equipment and tenant improvement financing agreement with Meier Mitchell &
Company providing up to $17 million of credit and (ii) the equipment and tenant
improvement financing agreement with Comdisco, Inc. providing up to $17 million
of credit, each of which is secured by all of the tangible and intangible assets
relating to assets financed by the lender under the applicable agreement.

             "fair market value" means the price that would be paid in an
arm's-length transaction between an informed and willing seller under no
compulsion to sell and an informed and willing buyer under no compulsion to buy,
as determined in good faith by the Board of Directors, whose determination shall
be conclusive if evidenced by a Board Resolution.

             "Foreign Subsidiary" mean any Subsidiary of the Company that is
organized under the laws of any jurisdiction, other than under the laws of the
United States or any state, territory or political subdivision thereof, and its
primary business and operation do not include any of the U.S.-based business and
operations conducted by the Company and its Restricted Subsidiaries.

             "GAAP" means generally accepted accounting principles in the United
States of America as in effect as of the Closing Date, including, without
limitation, those set forth in the opinions and pronouncements of the Accounting
Principles Board of the American Institute of Certified Public Accountants and
statements and pronouncements of the Financial Accounting

<PAGE>   16
                                       10

Standards Board or in such other statements by such other entity as approved by
a significant segment of the accounting profession. All ratios and computations
contained or referred to in this Indenture shall be computed in conformity with
GAAP applied on a consistent basis, except that calculations made for purposes
of determining compliance with the terms of the covenants and with other
provisions of this Indenture shall be made without giving effect to (i) the
amortization of any expenses incurred in connection with the offering of the
Units and (ii) except as otherwise provided, the amortization of any amounts
required or permitted by Accounting Principles Board Opinion Nos. 16 and 17.

             "Government Securities" means the direct obligations of,
obligations fully guaranteed by, or participations in pools consisting solely of
obligations of or obligations guaranteed by the United States of America for the
payment of which guarantee or obligations the full faith and credit of the
United States of America is pledged and which are not callable or redeemable at
the option of the issuer thereof.

             "Guarantee" means any obligation, contingent or otherwise, of any
Person directly or indirectly guaranteeing any Indebtedness of any other Person
and, without limiting the generality of the foregoing, any obligation, direct or
indirect, contingent or otherwise, of such Person (i) to purchase or pay (or
advance or supply funds for the purchase or payment of) such Indebtedness of
such other Person (whether arising by virtue of partnership arrangements, or by
agreements to keep-well, to purchase assets, goods, securities or services
(unless such purchase arrangements are on arm's-length terms and are entered
into in the ordinary course of business), to take-or-pay, or to maintain
financial statement conditions or otherwise) or (ii) entered into for purposes
of assuring in any other manner the obligee of such Indebtedness of the payment
thereof or to protect such obligee against loss in respect thereof (in whole or
in part); provided that the term "Guarantee" shall not include endorsements for
collection or deposit in the ordinary course of business. The term "Guarantee"
used as a verb has a corresponding meaning.

             "Guaranteed Indebtedness" has the meaning provided in Section 4.07
hereof.

             "Holder" or "Noteholder" means the registered holder of any Note.

             "Incur" means, with respect to any Indebtedness, to incur, create,
issue, assume, Guarantee or otherwise, directly or indirectly, become liable for
or with respect to, or become responsible for, the payment of, contingently or
otherwise, such Indebtedness, including an "Incurrence" of Acquired
Indebtedness; provided that neither the accrual of interest nor the accretion of
original issue discount shall be considered an Incurrence of Indebtedness.

             "Indebtedness" means, with respect to any Person at any date of
determination (without duplication), (i) all indebtedness of such Person for
borrowed money, (ii) all obligations of such Person evidenced by bonds,
debentures, notes or other similar instruments, (iii) all obligations of such
Person in respect of letters of credit or other similar instruments (including

<PAGE>   17
                                       11

reimbursement obligations with respect thereto, but excluding obligations with
respect to letters of credit (including trade letters of credit) securing
obligations (other than obligations described in (i) or (ii) above or (v), (vi)
or (vii) below) entered into in the ordinary course of business of such Person
to the extent such letters of credit are not drawn upon or, if drawn upon, to
the extent such drawing is reimbursed no later than the third Business Day
following receipt by such Person of a demand for reimbursement), (iv) all
obligations of such Person to pay the deferred and unpaid purchase price of
property or services, which purchase price is due more than six months after the
date of placing such property in service or taking delivery and title thereto or
the completion of such services, except Trade Payables, (v) all Capitalized
Lease Obligations of such Person, (vi) all Indebtedness of other Persons secured
by a Lien on any asset of such Person, whether or not such Indebtedness is
assumed by such Person; provided that the amount of such Indebtedness shall be
the lesser of (A) the fair market value of such asset at such date of
determination and (B) the amount of such Indebtedness, (vii) all Indebtedness of
other Persons Guaranteed by such Person to the extent such Indebtedness is
Guaranteed by such Person, (viii) to the extent not otherwise included in this
definition, obligations under Currency Agreements and Interest Rate Agreements
(other than Commodity Agreements, Currency Agreements and Interest Rate
Agreements designed solely to protect the Company or its Restricted Subsidiary
against fluctuations in commodity prices, foreign currency exchange rates or
interest rates and that do not increase the Indebtedness of the obligor
outstanding at any time other than as a result of fluctuations in commodity
prices, foreign currency exchange rates or interest rates or by reason of fees,
indemnities and compensation payable thereunder); and (ix) Disqualified Stock of
such Person and Preferred Stock of such Person's Restricted Subsidiaries. The
amount of Indebtedness of any Person at any date shall be the outstanding
balance at such date of all unconditional obligations, as described above and,
with respect to contingent obligations, the maximum liability upon the
occurrence of the contingency giving rise to the obligation, provided that (A)
the amount outstanding at any time of any Indebtedness issued with original
issue discount is the face amount of such Indebtedness less the remaining
unamortized portion of the original issue discount of such Indebtedness at the
time as determined in conformity with GAAP, (B) money borrowed and set aside at
the time of the Incurrence of any Indebtedness in order to prefund the payment
of the interest on such Indebtedness shall not be deemed to be "Indebtedness" so
long as such money is held to secure the payment of such interest and (C)
Indebtedness shall not include (v) any liability for federal, state, local or
other taxes, (w) performance, surety or appeal bonds provided in the ordinary
course of business, (x) agreements providing for indemnification, adjustment of
purchase price or similar obligations, or Guarantees or letters of credit,
surety bonds or performance bonds securing any obligations of the Company or any
of its Restricted Subsidiaries pursuant to such agreements, in any case Incurred
in connection with the disposition of any business, assets or Restricted
Subsidiary (other than Guarantees of Indebtedness Incurred by any Person
acquiring all or any portion of such business, assets or Restricted Subsidiary
for the purpose of financing such acquisition), so long as the principal amount
does not exceed the gross proceeds actually received by the Company or any
Restricted Subsidiary in connection with such disposition, (y) liabilities

<PAGE>   18
                                       12

incurred in connection with leases properly classified as operating leases in
accordance with GAAP or (z) accrued expenses.

             "Indenture" means this Indenture as originally executed or as it
may be amended or supplemented from time to time by one or more indentures
supplemental to this Indenture entered into pursuant to the applicable
provisions of this Indenture.

             "Institutional Accredited Investor" shall mean an "accredited
investor" of the type described in Rule 501(a)(1), (2), (3) or (7) under the
Securities Act.

             "Interest Payment Date" means each semiannual interest payment date
on March 15 and September 15 of each year, commencing September 15, 2000.

             "Interest Rate Agreement" means any interest rate protection
agreement, interest rate future agreement, interest rate option agreement,
interest rate swap agreement, interest rate cap agreement, interest rate collar
agreement, interest rate hedge agreement, option or future contract or other
similar agreement or arrangement.

             "Investment" in any Person means any direct or indirect advance,
loan or other extension of credit (including, without limitation, by way of
Guarantee or similar arrangement; but excluding advances to customers or
suppliers in the ordinary course of business that are, in conformity with GAAP,
recorded as accounts receivable on the balance sheet of the Company or its
Restricted Subsidiaries and endorsements for collection or deposit arising in
the ordinary course of business) or capital contribution to (by means of any
transfer of cash or other property to others or any payment for property or
services for the account or use of others), or any purchase or acquisition of
Capital Stock, bonds, notes, debentures or other similar instruments issued by,
such Person and shall include (i) the designation of a Restricted Subsidiary as
an Unrestricted Subsidiary and (ii) the retention of the Capital Stock (or any
other Investment) by the Company or any of its Restricted Subsidiaries, of (or
in) any Person that has ceased to be a Restricted Subsidiary, including, without
limitation or by reason of any transaction permitted by clause (iii) of Section
4.06 hereof. For purposes of the definition of "Unrestricted Subsidiary" and
Section 4.04, (a) the amount of or a reduction in an Investment shall be equal
to the fair market value thereof at the time such Investment is made or reduced
and (b) in the event the Company or a Restricted Subsidiary makes an Investment
by transferring assets to any Person and as part of such transaction receives
Net Cash Proceeds, the amount of such Investment shall be the fair market value
of the assets less the amount of Net Cash Proceeds so received.

             "Lien" means any mortgage, pledge, security interest, encumbrance,
lien or fixed or floating charge of any kind (including, without limitation, any
conditional sale or other title retention agreement or lease in the nature
thereof or any agreement to give any security interest); provided, however, that
the term "Lien" shall not include any Lease, properly classified as an operating
lease in accordance with GAAP.

<PAGE>   19
                                       13

             "Moody's" means Moody's Investors Service, Inc. and its successors.

             "Net Cash Proceeds" means, (a) with respect to any Asset Sale, the
proceeds of such Asset Sale in the form of cash or cash equivalents, including
payments in respect of deferred payment obligations (to the extent corresponding
to the principal, but not interest, component thereof) when received in the form
of cash or cash equivalents and proceeds from the conversion of other property
received when converted to cash or cash equivalents, net of (i) brokerage
commissions and other fees and expenses (including fees and expenses of counsel
and investment bankers) related to such Asset Sale, (ii) provisions for all
taxes (whether or not such taxes will actually be paid or are payable) as a
result of such Asset Sale without regard to the consolidated results of
operations of the Company and its Restricted Subsidiaries, taken as a whole,
(iii) payments made to repay Indebtedness or any other obligation outstanding at
the time of such Asset Sale that either (A) is secured by a Lien on the property
or assets sold or (B) is required to be paid as a result of such sale, and (iv)
appropriate amounts to be provided by the Company or any Restricted Subsidiary
as a reserve against any liabilities associated with such Asset Sale, including,
without limitation, pension and other post-employment benefit liabilities,
liabilities related to environmental matters and liabilities under any
indemnification obligations associated with such Asset Sale, all as determined
in conformity with GAAP, and (b) (i) with respect to any issuance or sale of
Capital Stock, the proceeds of such issuance or sale in the form of cash or cash
equivalents, including payments in respect of deferred payment obligations (to
the extent corresponding to the principal, but not interest, component thereof)
when received in the form of cash or cash equivalents and proceeds from the
conversion of other property received when converted to cash or cash
equivalents, and (ii) with respect to any Indebtedness that is converted into,
or exchanged for, Capital Stock (other than Disqualified Stock), the proceeds of
such issuance or sale of Indebtedness in the form of cash or cash equivalents
and proceeds from the conversion of other property received when converted to
cash or cash equivalents, in each case with respect to clauses (i) and (ii), net
of attorney's fees, accountants' fees, underwriters' or placement agents' fees,
discounts or commissions and brokerage, consultant and other fees incurred in
connection with such issuance or sale and net of taxes paid or payable as a
result thereof.

             "Note Guarantee" has the meaning provided in Section 4.07.

             "Note Register" has the meaning provided in Section 2.04.

             "Notes" means any of the Notes, as defined in the first paragraph
of the recitals hereof, that are authenticated and delivered under this
Indenture. For all purposes of this Indenture, the term "Notes" shall include
any Exchange Notes to be issued and exchanged for any Notes pursuant to the
Registration Rights Agreement and this Indenture and, for purposes of this
Indenture, all Notes and Exchange Notes shall vote together as one series of
Notes under this Indenture.

<PAGE>   20
                                       14

             "Offer to Purchase" means an offer to purchase Notes by the Company
from the Holders commenced by mailing a notice to the Trustee and each Holder
stating: (i) the covenant pursuant to which the offer is being made and that all
Notes validly tendered will be accepted for payment on a pro rata basis; (ii)
the purchase price and the date of purchase (which shall be a Business Day no
earlier than 30 days nor later than 60 days from the date such notice is mailed)
(the "Payment Date"); (iii) that any Note not tendered will continue to accrue
interest pursuant to its terms; (iv) that, unless the Company defaults in the
payment of the purchase price, any Note accepted for payment pursuant to the
Offer to Purchase shall cease to accrue interest on and after the Payment Date;
(v) that Holders electing to have a Note purchased pursuant to the Offer to
Purchase will be required to surrender the Note, together with the form entitled
"Option of the Holder to Elect Purchase" on the reverse side of the Note
completed, to the Paying Agent at the address specified in the notice prior to
the close of business on the Business Day immediately preceding the Payment
Date; (vi) that Holders will be entitled to withdraw their election if the
Paying Agent receives, not later than the close of business on the third
Business Day immediately preceding the Payment Date, a telegram, facsimile
transmission or letter setting forth the name of such Holder, the principal
amount of Notes delivered for purchase and a statement that such Holder is
withdrawing his election to have such Notes purchased; and (vii) that Holders
whose Notes are being purchased only in part will be issued new Notes equal in
principal amount to the unpurchased portion of the Notes surrendered; provided
that each Note purchased and each new Note issued shall be in a principal amount
of $1,000 or integral multiples of $1,000. On the Payment Date, the Company
shall (i) accept for payment on a pro rata basis Notes or portions thereof
tendered pursuant to an Offer to Purchase; (ii) deposit with the Paying Agent
money sufficient to pay the purchase price of all Notes or portions thereof so
accepted; and (iii) deliver, or cause to be delivered, to the Trustee all Notes
or portions thereof so accepted together with an Officers' Certificate
specifying the Notes or portions thereof accepted for payment by the Company.
The Paying Agent shall promptly mail to the Holders of Notes so accepted payment
in an amount equal to the purchase price, and the Trustee shall promptly
authenticate and mail to such Holders a new Note equal in principal amount to
any unpurchased portion of the Note surrendered; provided that each Note
purchased and each new Note issued shall be in a principal amount of $1,000 or
an integral multiple thereof. The Company will publicly announce the results of
an Offer to Purchase as soon as practicable after the Payment Date. The Trustee
shall act as the Paying Agent for an Offer to Purchase. The Company will comply
with Rule 14e-1 under the Exchange Act and any other securities laws and
regulations thereunder to the extent such laws and regulations are applicable,
in the event that the Company is required to repurchase Notes pursuant to an
Offer to Purchase.

             "Officer" means, with respect to the Company, (i) the Chairman of
the Board, the Vice Chairman of the Board, the President, the Chief Executive
Officer, the Chief Financial Officer or a Vice President, and (ii) the Treasurer
or any Assistant Treasurer, or the Secretary or any Assistant Secretary of the
Company.

<PAGE>   21
                                       15

             "Officers' Certificate" means a certificate signed by one Officer
listed in clause (i) of the definition thereof and one Officer listed in clause
(ii) of the definition thereof; provided, however, that any such certificate may
be signed by any two of the Officers listed in clause (i) of the definition
thereof in lieu of being signed by one Officer listed in clause (i) of the
definition thereof and one Officer listed in clause (ii) of the definition
thereof. Each Officers' Certificate (other than certificates provided pursuant
to TIA Section 314(a)(4)) shall include the statements provided for in TIA
Section 314(e).

             "Opinion of Counsel" means a written opinion signed by legal
counsel who may be an employee of or counsel to the Company. Each such Opinion
of Counsel shall include the statements provided for in TIA Section 314(e).

             "Participant" means, with respect to DTC, a Person who has an
account with DTC (and, with respect to DTC, shall include Euroclear and Cedel).

             "Paying Agent" has the meaning provided in Section 2.04, except
that, for the purposes of Article Eight, the Paying Agent shall not be the
Company or a Subsidiary of the Company or an Affiliate of any of them).

             "Payment Date" means the date of purchase, which shall be a
Business Day no earlier than 30 days nor later than 60 days from the date of
notice is mailed pursuant to an Offer to Purchase.

             "Permitted Business" means (i) the business of designing,
constructing, owning, operating and leasing colocation facilities for
telecommunications, data communications and Internet-based businesses and
businesses reasonably related, complementary or incidental thereto; (ii) server
and other based hosting; (iii) the management of computer systems, data
networks, or telecommunications systems; (iv) providing direct connections,
switched interconnections and related services to third parties as well as
related operations and businesses; (v) technology services, equipment staging,
or software services for Internet Protocol or successor protocol based networks;
and (vi) other businesses reasonably related, ancillary, supplemental or
incidental to any of the foregoing or reasonable extensions thereof.

             "Permitted Investment" means (i) an Investment in the Company or a
Restricted Subsidiary or a Person which will, upon the making of such
Investment, become a Restricted Subsidiary or be merged or consolidated with or
into or transfer or convey all or substantially all its assets to the Company or
a Restricted Subsidiary; provided that such Person's primary business is
related, ancillary or complementary to a Permitted Business; (ii) Temporary Cash
Investments; (iii) payroll, travel and similar advances to cover matters that
are expected at the time of such advances ultimately to be treated as expenses
in accordance with GAAP, or loans or guarantees to officers, directors and
employees approved by the Board of Directors of the Company or any committee
thereof, in connection with the relocation of such persons; (iv) stock,

<PAGE>   22
                                       16

obligations or securities received in satisfaction of judgments;(v) an
Investment in an Unrestricted Subsidiary consisting solely of an Investment in
another Unrestricted Subsidiary; (vi) Commodity Agreements, Interest Rate
Agreements and Currency Agreements designed solely to protect the Company or its
Restricted Subsidiaries against fluctuations in commodity prices, interest rates
or foreign currency exchange rates; (vii) any Investment received (a) in
satisfaction of judgments or (b) as payment on a claim made in connection with
any bankruptcy, liquidation, receivership or other insolvency proceeding; (viii)
Investments in (a) prepaid expenses and negotiable instruments held for
collection, (b) Investments obtained in exchange or settlement of accounts
receivable for which the Company or any Restricted Subsidiary has determined
that the collection is questionable and (c) lease, utility and worker
compensation, performance and other similar deposits arising in the ordinary
course of business; (ix) Strategic Investments provided that the aggregate
amount of Investments made pursuant to this clause (ix) shall not exceed the
greater of $20.0 million and 2 1/2% of the Company's Total Common Equity, at any
one time outstanding; (x) Investments, to the extent the consideration therefore
is the licensing or disclosure of intellectual property or know-how; and (xi)
other Investments not to exceed $5.0 million at any one time outstanding.

             "Permitted Liens" means: (i) Liens incurred or deposits made to
secure the performance of tenders, bids, leases, statutory or regulatory
obligations, bankers' acceptances, surety and appeal bonds, government
contracts, performance and return-of-money bonds and other obligations of a
similar nature incurred in the ordinary course of business (exclusive of
obligations for the payment of borrowed money); (ii) Liens (including extensions
and renewals thereof) upon real or personal property acquired after the Closing
Date; provided that (a) such Lien is created solely for the purpose of securing
Indebtedness Incurred pursuant to clause (7) of the second paragraph of part (a)
of Section 4.03, and such Lien is created prior to, at the time of or within six
months after the later of the acquisition, the completion of construction or the
commencement of full operation of such property, (b) the principal amount of the
Indebtedness secured by such Lien does not exceed 100% of such cost, and (c) any
such Lien shall not extend to or cover any property or assets other than such
item of property or assets or attachments, accessions or proceeds thereof, and
any improvements on such item; (iii) any interest or title of a lessor in the
property subject to any Capitalized Lease or operating lease; (iv) Liens arising
from filing Uniform Commercial Code financing statements regarding leases; (v)
Liens on property of, or on shares of Capital Stock or Indebtedness of, any
Person existing at the time such Person becomes a Restricted Subsidiary of the
Company or is merged with or into or consolidated with the Company or any
Restricted Subsidiary of the Company; provided that such Liens are not Incurred
in contemplation of such acquisition, merger or consolidation and do not extend
to or cover any property or assets of the Company or any Restricted Subsidiary
other than those of the Person acquired by, merged into or consolidated with the
Company or any Restricted Subsidiary; (vi) Liens in favor of the Company or any
Restricted Subsidiary; (vii) Liens on property existing at the time of
acquisition thereof by the Company or any Restricted Subsidiary of the Company;
provided that such Liens are not incurred in contemplation of such acquisition
and do not extend to any asset other than the assets acquired; (viii) Liens
securing reimbursement obligations with

<PAGE>   23
                                       17

respect to letters of credit that encumber documents and other property relating
to such letters of credit and the products and proceeds thereof or any cash
collateral; (ix) Liens encumbering customary initial deposits and margin
deposits, and other Liens that are within the general parameters customary in
the industry and incurred in the ordinary course of business, in each case,
securing Indebtedness under Commodity Agreements, Interest Rate Agreements and
Currency Agreements designed solely to protect the Company or any of its
Restricted Subsidiaries from fluctuations in interest rates, currencies or the
price of commodities; (x) Liens arising out of conditional sale, title
retention, consignment or similar arrangements for the sale of goods entered
into by the Company or any of its Restricted Subsidiaries in the ordinary course
of business in accordance with the past practices of the Company and its
Restricted Subsidiaries prior to the Closing Date; (xi) Liens on shares of
Capital Stock of any Unrestricted Subsidiary to secure Indebtedness of such
Unrestricted Subsidiary; (xii) Liens on, or sales of, accounts receivable; and
(xiii) licenses.

             "Person" means an individual, a corporation, a partnership, a
limited liability company, a joint venture, an association, a trust, an
unincorporated organization or any other entity or organization, including a
government or political subdivision or an agency or instrumentality thereof.

             "Pledge Account" means an account established with the Trustee
pursuant to the terms of the Pledge Agreement for the deposit of the Pledged
Securities purchased by the Company with a portion of the proceeds from the sale
of the Notes.

             "Pledge Agreement" means the Collateral Pledge and Security
Agreement, dated as of the Closing Date, made by the Company in favor of the
Trustee, governing the disbursement of funds from the Pledge Account, as such
agreement may be amended, restated, supplemented or otherwise modified from time
to time.

             "Pledged Securities" means the Government Securities to be
purchased by the Company and held in the Pledge Account in accordance with the
Pledge Agreement.

             "Preferred Stock" or "preferred stock" means, with respect to any
Person, any and all shares, interests, participation or other equivalents
(however designated, whether voting or non-voting) of such Person's preferred or
preference stock, whether now outstanding or issued after the date of this
Indenture, including, without limitation, all series and classes of such
preferred or preference stock.

             "principal" of a debt security, including the Notes, means the
principal amount due on the Stated Maturity as shown on such debt security.

             "Private Placement Legend" means the legend initially set forth on
the Notes in the form set forth in Section 2.02(a).

<PAGE>   24
                                       18

             "Public Equity Offering" means an underwritten primary public
offering of Common Stock of the Company pursuant to an effective registration
statement under the Securities Act.

             A "Public Market" shall be deemed to exist if (i) a Public Equity
Offering has been consummated and (ii) at least 15% of the total issued and
outstanding Common Stock of the Company has been distributed by means of an
effective registration statement under the Securities Act or sales pursuant to
Rule 144 or Rule 701 under the Securities Act.

             "Purchase Agreement" has the meaning provided in the recitals to
this Indenture.

             "QIB" means a "qualified institutional buyer" as defined in Rule
144A.

             "Redemption Date" when used with respect to any Note or part
thereof to be redeemed, means the date fixed for such redemption by or pursuant
to the terms of the Notes and this Indenture.

             "Redemption Price" when used with respect to any Note or part
thereof to be redeemed, means the price at which such Note is to be redeemed
pursuant to the terms of the Notes and this Indenture.

             "Registrar" has the meaning provided in Section 2.04.

             "Registration Rights Agreement" means the Registration Rights
Agreement, dated as of March 10, 2000, between the Company and Goldman, Sachs &
Co., on behalf of itself and Bear, Stearns & Co. Inc., Chase Securities Inc.,
Deutsche Bank Securities Inc., Warburg Dillon Read LLC and Jefferies & Company,
Inc. relating to the Notes.

             "Registration Statement" means any registration statement of the
Company that covers any of the Exchange Notes, and all amendments and
supplements to any such Registration Statement, including post-effective
amendments, in each case including the prospectus contained therein, all
exhibits thereto and all material incorporated by reference therein.

             "Regular Record Date" for the interest payable on any Interest
Payment Date means March 1 or September 1 (whether or not a Business Day), as
the case may be, next preceding such Interest Payment Date.

             "Replacement Assets" means, on any date, property or assets (other
than current assets) of a nature or type or that are used in a business (or an
Investment in a company having property or assets of a nature or type, or
engaged in a business) that is a Permitted Business.

<PAGE>   25
                                       19

             "Responsible Officer", when used with respect to the Trustee, means
any officer of the Trustee with direct responsibility for the administration of
this Indenture, and also means, with respect to a particular corporate trust
matter, any other officer to whom such matter is referred because of his or her
knowledge of and familiarity with the particular subject.

             "Global Note" has the meaning provided in Section 2.01.

             "Restricted Payments" has the meaning provided in Section 4.04.

             "Restricted Subsidiary" means any Subsidiary of the Company other
than an Unrestricted Subsidiary.

             "Rule 144A" means Rule 144A under the Securities Act.

             "Securities Act" means the Securities Act of 1933, as amended.

             "Separation Date" has the meaning provided in the recitals to this
Indenture.

             "Shelf Registration Statement" means the Shelf Registration
Statement as defined in the Registration Rights Agreement.

             "Significant Subsidiary" means, at any date of determination, any
Restricted Subsidiary that, together with its Subsidiaries, (i) for the most
recent fiscal year of the Company, accounted for more than 10% of the
consolidated revenues of the Company and its Restricted Subsidiaries or (ii) as
of the end of such fiscal year, was the owner of more than 10% of the
consolidated assets of the Company and its Restricted Subsidiaries, all as set
forth on the most recently available consolidated financial statements of the
Company for such fiscal year.

             "S&P" means Standard & Poor's Ratings Group, a division of The
McGraw-Hill Corporation, and its successors.

             "Stated Maturity" means (i) with respect to any debt security, the
date specified in such debt security as the fixed date on which the final
installment of principal of such debt security is due and payable and (ii) with
respect to any scheduled installment of principal of or interest on any debt
security, the date specified in such debt security as the fixed date on which
such installment is due and payable.

             "Strategic Investment" means any Investment in any Person (other
than an Unrestricted Subsidiary) whose primary business is a Permitted Business,
and such Investment is determined by the Board of Directors of the Company to
promote or significantly benefit the businesses of the Company and its
Restricted Subsidiaries as of the date of such Investment.

<PAGE>   26
                                       20

             "Subsidiary" means, with respect to any Person, any corporation,
association or other business entity of which more than 50% of the voting power
of the outstanding Voting Stock is owned, directly or indirectly, by such Person
and one or more other Subsidiaries of such Person.

             "Subsidiary Guarantor" means any Restricted Subsidiary which
provides a Note Guarantee of the Company's obligations under this Indenture and
Notes.

             "Temporary Cash Investment" means any of the following: (i) direct
obligations of the United States of America or any agency thereof or obligations
fully and unconditionally guaranteed by the United States of America or any
agency thereof, in each case maturing within one year; (ii) time deposit
accounts, certificates of deposit and money market deposits maturing (with
respect to all such items outstanding at any given time) within an average of
180 days of the date of acquisition thereof (provided that each such item
matures within 18 months of the date of acquisition thereof) issued by a bank or
trust company which is organized under the laws of the United States of America,
any state thereof or any foreign country recognized by the United States of
America, and which bank or trust company has capital, surplus and undivided
profits aggregating in excess of $100 million (or the foreign currency
equivalent thereof) and has outstanding debt which is rated "A" (or such similar
equivalent rating) or higher by at least one nationally recognized statistical
rating organization (as defined in Rule 436 under the Securities Act) or any
money market fund sponsored by a registered broker dealer or mutual fund
distributor; (iii) repurchase obligations with a term of not more than 30 days
for underlying securities of the types described in clause (i) above entered
into with a bank or trust company meeting the qualifications described in clause
(ii) above; (iv) commercial paper, maturing not more than one year after the
date of acquisition, issued by a corporation (other than an Affiliate of the
Company) organized and in existence under the laws of the United States of
America, any state thereof or any foreign country recognized by the United
States of America with a rating at the time as of which any investment therein
is made of "P-1" (or higher) according to Moody's or "A-1" (or higher) according
to S&P; (v) securities with maturities of six months or less from the date of
acquisition issued or fully and unconditionally guaranteed by any state,
commonwealth or territory of the United States of America, or by any political
subdivision or taxing authority thereof, and rated at least "A" by S&P or
Moody's; and (vi) any mutual fund that has at least 95% of its assets
continuously invested in investments of the types described in clauses (i)
through (v) above.

             "TIA" or "Trust Indenture Act" means the Trust Indenture Act of
1939, as amended (15 U.S. Code SECTIONS 77aaa-77bbb), as in effect on the date
this Indenture was executed, except as provided in Section 9.06; provided,
however, that, in the event the Trust Indenture Act of 1939 is amended after
such date, "TIA" or "Trust Indenture Act" means, to the extent required by any
such amendment, the Trust Indenture Act of 1939 as so amended.

<PAGE>   27
                                       21

             "Total Common Equity" of any Person means, as of any date of
determination the product of (i) the aggregate number of outstanding primary
shares of Common Stock of such Person on such day (which shall not include any
options or warrants on, or securities convertible or exchangeable into, shares
of Common Stock of such Person) and (ii) the average Closing Price of such
Common Stock over the 20 consecutive Trading Days immediately preceding such
day. If no such Closing Price exists with respect to shares of any such class,
the value of such shares for purposes of Clause (ii) of the preceding sentence
shall be determined by the Board of Directors of the Company in good faith and
evidenced by a resolution of the Board of Directors filed with the Trustee.

             "Trade Payables" means, with respect to any Person, any accounts
payable or any other indebtedness or monetary obligation to trade creditors
created, assumed or Guaranteed by such Person or any of its Subsidiaries arising
in the ordinary course of business in connection with the acquisition of goods
or services.

             "Trading Day" with respect to a securities exchange or automated
quotation system means a day on which such exchange or system is open for a full
day of trading.

             "Transaction Date" means, with respect to the Incurrence of any
Indebtedness or Issuance of Incurrence of Preferred Stock, the date such
Indebtedness is to be Incurred or such Preferred Stock is to be issued or
Incurred and, with respect to any Restricted Payment, the date such Restricted
Payment is to be made.

             "Trustee" means the party named as such in the first paragraph of
this Indenture until a successor replaces it in accordance with the provisions
of Article Seven of this Indenture, and thereafter means such successor.

             "Unit" has the meaning provided in the recitals to this Indenture.

             "United States Bankruptcy Code" means the Bankruptcy Reform Act of
1978, as amended and as codified in Title 11 of the United States Code, as
amended from time to time hereafter, or any successor federal bankruptcy law.

             "Unrestricted Subsidiary" means

             (i) any Subsidiary of the Company that at the time of determination
        shall be designated an Unrestricted Subsidiary by the Board of Directors
        in the manner provided below; and

             (ii) any Subsidiary of an Unrestricted Subsidiary.

<PAGE>   28
                                       22

The Board of Directors may designate any Restricted Subsidiary (including any
newly acquired or newly formed Subsidiary of the Company) to be an Unrestricted
Subsidiary unless such Subsidiary owns any Capital Stock of, or owns or holds
any Lien on any property of, the Company or any Restricted Subsidiary; provided
that

             (A) any Guarantee by or the Company or any Restricted Subsidiary of
        any Indebtedness of the Subsidiary being the Company so designated shall
        be deemed an "Incurrence" of such Indebtedness and an "Investment" by
        the Company or such Restricted Subsidiary (or both, if applicable) at
        the time of such designation;

             (B) either (I) the Subsidiary to be so designated has total assets
        of $1,000 or less or (II) if such Subsidiary has assets greater than
        $1,000, such designation would be permitted under Section 4.04; and

             (C) if applicable, the Incurrence of Indebtedness and the
        Investment referred to in clause (A) of this provision would be
        permitted under Section 4.03 and Section 4.04.

        The Board of Directors may designate any Unrestricted Subsidiary to be a
Restricted Subsidiary; provided that

             (a) no Default or Event of Default shall have occurred and be
        continuing at the time of or after giving effect to such designation and

             (b) all Liens and Indebtedness of such Unrestricted Subsidiary
        outstanding immediately after such designation would, if Incurred at
        such time, have been permitted to be Incurred (and shall be deemed to
        have been Incurred) for all purposes of this Indenture.

        Any such designation by the Board of Directors shall be evidenced to the
Trustee by promptly filing with the Trustee a copy of the Board Resolution
giving effect to such designation and an Officers' Certificate certifying that
such designation complied with the forgoing provisions.

             "U.S. Government Obligations" means securities that are (i) direct
obligations of the United States of America for the payment of which its full
faith and credit is pledged or (ii) obligations of a Person controlled or
supervised by and acting as an agency or instrumentality of the United States of
America the payment of which is unconditionally guaranteed as a full faith and
credit obligation by the United States of America, which, in either case, are
not callable or redeemable at the option of the issuer thereof at any time prior
to the Stated Maturity of the Notes, and shall also include depository receipts
issued by a bank or trust company as custodian with respect to any such U.S.
Government Obligation or a specific payment of interest on or principal of any
such U.S. Government Obligation held by such custodian for the account of the
holder of a depository receipt; provided that (except as required by law) such
custodian is not

<PAGE>   29
                                       23

authorized to make any deduction from the amount payable to the holder of such
depository receipt from any amount received by the custodian in respect of the
U.S. Government Obligation or the specific payment of interest on or principal
of the U.S. Government Obligation evidenced by such depository receipt.

             "Voting Stock" means, with respect to any Person, Capital Stock of
any class or kind ordinarily having the power to vote for the election of
directors, managers or other voting members of the governing body of such
Person.

             "Warrant" has the meaning provided in the recitals to this
Indenture.

             "Wholly Owned" means, with respect to any Subsidiary of any Person,
the ownership of all of the outstanding Capital Stock of such Subsidiary (other
than any director's qualifying shares or Investments by foreign nationals
mandated by applicable law) by such Person or one or more Wholly Owned
Subsidiaries of such Person.

             SECTION 1.02. Incorporation by Reference of Trust Indenture Act.
Whenever this Indenture refers to a provision of the TIA, the provision is
incorporated by reference in and made a part of this Indenture. The following
TIA terms used in this Indenture have the following meanings:

             "indenture securities" means the Notes;

             "indenture security holder" means a Holder or a Noteholder;

             "indenture to be qualified" means this Indenture;

             "indenture trustee" or "institutional trustee" means the Trustee;
        and

             "obligor" on the indenture securities means the Company or any
        other obligor on the Notes.

             All other TIA terms used in this Indenture that are defined by the
TIA, defined by TIA reference to another statute or defined by a rule of the
Commission and not otherwise defined herein have the meanings assigned to them
therein.

             SECTION 1.03. Rules of Construction. Unless the context otherwise
requires:

             (i) a term has the meaning assigned to it;

             (ii) an accounting term not otherwise defined has the meaning
        assigned to it in accordance with GAAP;

<PAGE>   30
                                       24

             (iii) "or" is not exclusive;

             (iv) words in the singular include the plural, and words in the
        plural include the singular;

             (v) provisions apply to successive events and transactions;

             (vi) "herein," "hereof" and other words of similar import refer to
        this Indenture as a whole and not to any particular Article, Section or
        other subdivision; and

             (vii) all references to Sections or Articles refer to Sections or
        Articles of this Indenture unless otherwise indicated.

                                   ARTICLE TWO
                                    THE NOTES

             SECTION 2.01. Form and Dating. The Notes and the Trustee's
certificate of authentication with respect thereto shall be substantially in the
form annexed hereto as Exhibit A, in the case of the Global Note, and Exhibit B,
in the case of a Certificated Note. The Notes may have such appropriate
insertions, omissions, substitutions and other variations as are required or
permitted by this Indenture and may have letters, notations, legends or
endorsements required by law, stock exchange agreements to which the Company is
subject or usage. Any portion of the text of any Note may be set forth on the
reverse thereof, with an appropriate reference thereto on the face of the Note.
The Company shall approve the form of the Notes and any notation, legend or
endorsement on the Notes. Each Note shall be dated the date of its
authentication.

             The terms and provisions contained in the form of the Notes annexed
hereto as Exhibits A and B shall constitute, and are hereby expressly made, a
part of this Indenture. Each of the Company and the Trustee, by its execution
and delivery of this Indenture, expressly agrees to the terms and provisions of
the Notes applicable to it and to be bound thereby.

             Notes offered and sold in reliance on Rule 144A shall be issued
initially in the form of one or more permanent global Notes in registered form,
substantially in the form set forth in Exhibit A (the "Global Note"), registered
in the name of a nominee of the Depository, deposited with the Trustee, as
custodian for the Depository, duly executed by the Company and authenticated by
the Trustee as hereinafter provided. The aggregate principal amount of a Global
Note may from time to time be increased or decreased by adjustments made on the
records of the Registrar as hereinafter provided.

             Notes which are transferred to Institutional Accredited Investors
which are not QIBs shall be issued in the form of permanent certificated Notes
in registered form in

<PAGE>   31
                                       25

substantially the form set forth in Exhibit B (the "Certificated Notes"). Notes
issued pursuant to Section 2.07 in exchange for interests in the Global Note
shall be in the form of the Certificated Note.

             The definitive Notes shall be typed, printed (commercially or
otherwise), lithographed or engraved or produced by any combination of these
methods or may be produced in any other manner permitted by the rules of any
securities exchange on which the Notes may be listed, all as determined by the
officers executing such Notes, as evidenced by their execution of such Notes.

             SECTION 2.02. Restrictive Legends. (a) Note Legends. Unless and
until a Note is exchanged for an Exchange Note or otherwise disposed of in
connection with an effective Registration Statement pursuant to the Registration
Rights Agreement, each Global Note and Certificated Note shall bear the legend
set forth below on the face thereof.

        THE SECURITIES EVIDENCED HEREBY HAVE NOT BEEN REGISTERED UNDER THE
        UNITED STATES SECURITIES ACT OF 1933, AS AMENDED (THE "SECURITIES ACT"),
        AND MAY NOT BE OFFERED, SOLD, PLEDGED OR OTHERWISE TRANSFERRED EXCEPT
        (1) TO A PERSON WHOM THE SELLER REASONABLY BELIEVES IS A QUALIFIED
        INSTITUTIONAL BUYER WITHIN THE MEANING OF RULE 144A UNDER THE SECURITIES
        ACT PURCHASING FOR ITS OWN ACCOUNT OR FOR THE ACCOUNT OF A QUALIFIED
        INSTITUTIONAL BUYER IN A TRANSACTION MEETING THE REQUIREMENTS OF RULE
        144A, (2) PURSUANT TO AN EXEMPTION FROM REGISTRATION UNDER THE
        SECURITIES ACT PROVIDED BY RULE 144 THEREUNDER (IF AVAILABLE), (3) TO AN
        INSTITUTIONAL ACCREDITED INVESTOR IN A TRANSACTION EXEMPT FROM THE
        REGISTRATION REQUIREMENTS UNDER REGULATION D UNDER THE SECURITIES ACT OR
        (4) PURSUANT TO AN EFFECTIVE REGISTRATION STATEMENT UNDER THE SECURITIES
        ACT, IN EACH CASE, IN ACCORDANCE WITH ALL APPLICABLE SECURITIES LAWS OF
        THE STATES OF THE UNITED STATES.

             (b) Global Note Legend. Each Global Note, whether or not an
Exchange Note, shall also bear the following legend on the face thereof:

        UNLESS THIS GLOBAL NOTE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF
        THE DEPOSITORY TRUST COMPANY TO THE COMPANY OR ITS AGENT FOR
        REGISTRATION OF TRANSFER, EXCHANGE OR PAYMENT, AND ANY NOTE ISSUED IS
        REGISTERED IN THE NAME OF CEDE & CO. OR TO SUCH OTHER ENTITY AS IS
        REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF THE DEPOSITORY TRUST
        COMPANY OR SUCH OTHER REPRESENTATIVE

<PAGE>   32
                                       26

        OF THE DEPOSITORY TRUST COMPANY OR SUCH OTHER NAME AS IS REQUESTED BY AN
        AUTHORIZED REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY (AND ANY
        PAYMENT HEREON IS MADE TO CEDE & CO. OR TO SUCH OTHER ENTITY AS IS
        REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF THE DEPOSITORY TRUST
        COMPANY), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR
        OTHERWISE BY OR TO ANY PERSON IS WRONGFUL SINCE THE REGISTERED OWNER
        HEREOF, CEDE & CO., HAS AN INTEREST HEREIN.

        TRANSFERS OF THIS GLOBAL NOTE SHALL BE LIMITED TO TRANSFERS IN WHOLE,
        BUT NOT IN PART, TO NOMINEES OF CEDE & CO. OR TO A SUCCESSOR THEREOF OR
        SUCH SUCCESSOR'S NOMINEE AND TRANSFERS OF PORTIONS OF THIS GLOBAL NOTE
        SHALL BE LIMITED TO TRANSFERS MADE IN ACCORDANCE WITH THE RESTRICTIONS
        SET FORTH IN SECTION 2.08 OF THE INDENTURE.

             Prior to the Separation Date, each Note shall bear the following
legend on the face thereof:

        THIS NOTE IS INITIALLY ISSUED AS PART OF AN ISSUANCE OF UNITS, EACH OF
        WHICH CONSISTS OF ONE NOTE AND ONE WARRANT INITIALLY ENTITLING THE
        HOLDER THEREOF TO PURCHASE 19.9718 SHARES OF COMMON STOCK, PAR VALUE
        $0.01 PER SHARE, OF COLO.COM (A "WARRANT"). PRIOR TO THE CLOSE OF
        BUSINESS UPON THE EARLIEST TO OCCUR OF (i) MARCH 10, 2001, (ii) 180 DAYS
        AFTER THE CLOSING DATE OF THE COMPANY'S INITIAL PUBLIC OFFERING, (iii)
        THE COMMENCEMENT OF AN EXCHANGE OFFER WITH RESPECT TO THE NOTES, (iv)
        THE EFFECTIVENESS OF A SHELF REGISTRATION STATEMENT WITH RESPECT TO THE
        NOTES, (v) THE COMMENCEMENT OF AN OFFER TO PURCHASE THE NOTES UPON A
        CHANGE OF CONTROL OR (vi) SUCH DATE AS DETERMINED BY GOLDMAN, SACHS &
        CO. IN ITS SOLE DISCRETION, THE NOTES EVIDENCED BY THIS CERTIFICATE MAY
        NOT BE TRANSFERRED OR EXCHANGED SEPARATELY FROM, BUT MAY BE TRANSFERRED
        OR EXCHANGED ONLY TOGETHER WITH, THE WARRANTS.

             SECTION 2.03. Execution, Authentication and Denominations. Subject
to Article Four and except as provided for in Section 2.15, the aggregate
principal amount of Notes (including Exchange Notes) which may be authenticated
and delivered under this Indenture is limited to $300,000,000. The Notes shall
be executed by two Officers of the Company, by facsimile or manual signature, in
the name and on behalf of the Company.

<PAGE>   33
                                       27

             If an Officer whose signature is on a Note no longer holds that
office at the time the Trustee or authenticating agent authenticates the Note,
the Note shall be valid nevertheless.

             A Note shall not be valid until the Trustee or authenticating agent
manually signs the certificate of authentication on the Note. The signature
shall be conclusive evidence that the Note has been authenticated under this
Indenture.

             At any time and from time to time after the execution of this
Indenture, the Trustee or an authenticating agent shall, upon receipt of a
Company Order, authenticate for original issue Notes in the aggregate principal
amount specified in such Company Order. Such Company Order shall specify the
amount of Notes to be authenticated, the date on which the issue of Notes is to
be authenticated and, in case of an issuance of Notes pursuant to Section 2.15,
shall certify that such issuance is in compliance with Article Four.

             The Trustee may appoint an authenticating agent reasonably
acceptable to the Company to authenticate Notes. Unless limited by the terms of
such appointment, an authenticating agent may authenticate Notes whenever the
Trustee may do so. Each reference in this Indenture to authentication by the
Trustee includes authentication by such authenticating agent. An authenticating
agent has the same rights as an Agent to deal with the Company or an Affiliate
of the Company.

             The Notes shall be issuable only in registered form without coupons
in principal amount of $1,000 and any integral multiple of $1,000 in excess
thereof.

             SECTION 2.04. Registrar and Paying Agent. The Company shall
maintain an office or agency in the City of New York where Notes may be
presented for registration of transfer or for exchange (the "Registrar"), an
office or agency in the City of New York where Notes may be presented for
payment (the "Paying Agent"), and an office or agency where notices and demands
to or upon the Company in respect of the Notes and this Indenture may be served,
which shall be in the City of New York. The Company shall cause the Registrar to
keep a register of the Notes and of their transfer and exchange (the "Note
Register"). The Company may have one or more co-Registrars and one or more
additional Paying Agents.

             The Company shall enter into an appropriate agency agreement with
any Agent not a party to this Indenture. The agreement shall implement the
provisions of this Indenture that relate to such Agent. The Company shall give
prompt written notice to the Trustee of the name and address of any such Agent
and any change in the address of such Agent. If the Company fails to maintain a
Registrar, Paying Agent and/or agent for service of notices and demands, the
Trustee shall act as such Registrar, Paying Agent and/or agent for service of
notices and demands for so long as such failure shall continue. The Company may
remove any Agent upon written notice to such Agent and the Trustee; provided
that no such removal shall become effective until (i) the acceptance of an
appointment by a successor Agent to such Agent as evidenced by an

<PAGE>   34
                                       28

appropriate agency agreement entered into by the Company and such successor
Agent and delivered to the Trustee or (ii) notification to the Trustee that the
Trustee shall serve as such Agent until the appointment of a successor Agent in
accordance with clause (i) of this proviso. The Company, any Subsidiary of the
Company, or any Affiliate of any of them may act as Paying Agent, Registrar or
co-Registrar, and/or agent for service of notice and demands; provided, however,
that neither the Company, a Subsidiary of the Company nor an Affiliate of any of
them shall act as Paying Agent in connection with the defeasance of the Notes or
the discharge of this Indenture under Article Eight.

             The Company initially appoints the Trustee as Registrar, Paying
Agent, authenticating agent and agent for service of notice and demands. If, at
any time, the Trustee is not the Registrar, the Registrar shall make available
to the Trustee on or before each Interest Payment Date and at such other times
as the Trustee may reasonably request, the names and addresses of the Holders as
they appear in the Note Register.

             SECTION 2.05. Paying Agent to Hold Money in Trust. Not later than
12:00 noon New York City time on each due date of the principal, premium, if
any, or interest on any Notes, the Company shall deposit with the Paying Agent
money in immediately available funds sufficient to pay such principal, premium,
if any, or interest so becoming due. The Company shall require each Paying
Agent, if any, other than the Trustee to agree in writing that such Paying Agent
shall hold in trust for the benefit of the Holders or the Trustee all money held
by the Paying Agent for the payment of principal of, premium, if any, or
interest on the Notes (whether such money has been paid to it by the Company or
any other obligor on the Notes), and that such Paying Agent shall promptly
notify the Trustee of any default by the Company (or any other obligor on the
Notes) in making any such payment. The Company at any time may require a Paying
Agent to pay all money held by it to the Trustee and account for any funds
disbursed, and the Trustee may at any time during the continuance of any payment
default, upon written request to a Paying Agent, require such Paying Agent to
pay all money held by it to the Trustee and to account for any funds disbursed.
Upon doing so, the Paying Agent shall have no further liability for the money so
paid over to the Trustee. If the Company or any Subsidiary of the Company or any
Affiliate of any of them acts as Paying Agent, it will, on or before each due
date of any principal of, premium, if any, or interest on the Notes, segregate
and hold in a separate trust fund for the benefit of the Holders a sum of money
sufficient to pay such principal, premium, if any, or interest so becoming due
until such sum of money shall be paid to such Holders or otherwise disposed of
as provided in this Indenture, and will promptly notify the Trustee of its
action or failure to act as required by this Section 2.05.

             SECTION 2.06. Transfer and Exchange. The Notes are issuable only in
registered form. The Notes shall initially be issued as part of an issue of
Units, each of which consists of one Note and one Warrant. Prior to the
Separation Date, the Notes may not be transferred or exchanged separately from,
but may be transferred or exchanged only together with, the Warrants issued in
connection with the Notes. A Holder may transfer a Note by written

<PAGE>   35
                                       29

application to the Registrar stating the name of the proposed transferee and
otherwise complying with the terms of this Indenture. No such transfer shall be
effected until, and such transferee shall succeed to the rights of a Holder only
upon registration of the transfer by the Registrar in the Note Register. Prior
to the registration of any transfer by a Holder as provided herein, the Company,
the Trustee, and any agent of the Company or the Trustee shall treat the Person
in whose name the Note is registered as the owner thereof for all purposes
whether or not the Note shall be overdue, and neither the Company, the Trustee,
nor any such agent shall be affected by notice to the contrary. Furthermore, any
Holder of a Global Note shall, by acceptance of such Global Note, agree that
transfers of beneficial interests in such Global Note may be effected only
through a book-entry system maintained by the Depository (or its agent), and
that ownership of a beneficial interest in the Note shall be required to be
reflected in a book entry. When Notes are presented to the Registrar or a
co-Registrar with a request to register the transfer or to exchange them for an
equal principal amount of Notes of other authorized denominations (including an
exchange of Notes for Exchange Notes), the Registrar shall register the transfer
or make the exchange as requested if its requirements for such transactions are
met; provided that no exchanges of Notes for Exchange Notes shall occur until a
Registration Statement shall have been declared effective by the Commission and
that any Notes that are exchanged for Exchange Notes shall be cancelled by the
Trustee. To permit registrations of transfers and exchanges in accordance with
the terms, conditions and restrictions hereof, the Company shall execute and the
Trustee shall authenticate Notes at the Registrar's request. No service charge
shall be made to any Holder for any registration of transfer or exchange or
redemption of the Notes, but the Company may require payment of a sum sufficient
to cover any transfer tax or similar governmental charge payable in connection
therewith (other than any such transfer taxes or other similar governmental
charge payable upon transfers, exchanges or redemptions pursuant to Section
2.11, 3.08, 4.11, 4.12 or 9.04).

             The Registrar shall not be required (i) to issue, register the
transfer of or exchange any Note during a period beginning at the opening of
business 15 days before the day of the mailing of a notice of redemption of
Notes selected for redemption under Section 3.03 or Section 3.08 and ending at
the close of business on the day of such mailing, or (ii) to register the
transfer of or exchange any Note so selected for redemption in whole or in part,
except the unredeemed portion of any Note being redeemed in part.

             SECTION 2.07. Book-Entry Provisions for Global Notes. (a) Each
Global Note initially shall (i) be registered in the name of the Depository for
such Global Note or the nominee of such Depository, (ii) be delivered to the
Trustee as custodian for such Depository and (iii) bear legends as set forth in
Section 2.02 hereof.

             Members of, or Participants in, the Depository ("Agent Members")
shall have no rights under this Indenture with respect to any Global Note held
on their behalf by the Depository, or the Trustee as its custodian, or under any
Global Note, and the Depository may be treated by the Company, the Trustee and
any agent of the Company or the Trustee as the absolute

<PAGE>   36
                                       30

owner of such Global Note for all purposes whatsoever. Notwithstanding the
foregoing, nothing herein shall prevent the Company, the Trustee or any agent of
the Company or the Trustee from giving effect to any written certification,
proxy or other authorization furnished by the Depository or impair, as between
the Depository and its Agent Members, the operation of customary practices
governing the exercise of the rights of a beneficial owner of any Note.

             (b) Transfers of a Global Note shall be limited to transfers of
such Global Note in whole, but not in part, to the Depository, its successors or
their respective nominees. Transfers of interests in one Global Note to parties
who will hold the interests through the same Global Note will be effected in the
ordinary way in accordance with the respective rules and operating procedures of
the DTC and the provisions of Section 2.08 hereof. In addition, Certificated
Notes shall be transferred to all beneficial owners in exchange for their
beneficial interests in a Global Note if (i) the Depository with respect to such
Global Note notifies the Company that it is unwilling or unable to continue as
Depository for the Global Note and a successor depository is not appointed by
the Company within 90 days of such notice or (ii) an Event of Default has
occurred and is continuing and the Registrar has received a request to the
foregoing effect from the Depository or the Trustee.

             (c) In connection with any transfer pursuant to paragraph (b) of
this Section 2.07 of a portion of the beneficial interests in a Global Note to
beneficial owners who are required to hold Certificated Notes, the Registrar
shall reflect on its books and records the date and a decrease in the principal
amount of such Global Note in an amount equal to the principal amount of the
beneficial interest in such Global Note to be transferred, and the Company shall
execute, and the Trustee shall authenticate and deliver, one or more
Certificated Notes of like tenor and amount.

             (d) In connection with the transfer of all the beneficial interests
in a Global Note to beneficial owners pursuant to paragraph (b) of this Section
2.07, the Global Note shall be deemed to be surrendered to the Trustee for
cancellation, and the Company shall execute, and the Trustee shall authenticate
and deliver, to each beneficial owner identified by the Depository in exchange
for its beneficial interest in the Global Note an equal aggregate principal
amount of Certificated Notes of authorized denominations.

             (e) Any Certificated Note delivered in exchange for an interest in
a Global Note pursuant to paragraph (b), (d) or (e) of this Section 2.07 shall,
except as otherwise provided by paragraphs (f)(i)(x) and (d) of Section 2.08
hereof, bear the legend regarding transfer restrictions applicable to the
Certificated Note set forth in Section 2.02.

             (f) The registered holder of a Global Note may grant proxies and
otherwise authorize any Person, including Agent Members and Persons that may
hold interests through Agent Members, to take any action which a Holder is
entitled to take under this Indenture or the Notes.

<PAGE>   37
                                       31

             (g) QIBs that are beneficial owners of interests in a Global Note
may receive Certificated Notes (which shall bear the Private Placement Legend if
required by Section 2.02) in accordance with the procedures of the Depository.
In connection with the execution, authentication and delivery of such
Certificated Notes, the Registrar shall reflect on its books and records a
decrease in the principal amount of the relevant Global Note equal to the
principal amount of such Certificated Notes and the Company shall execute and
the Trustee shall authenticate and deliver one or more Certificated Notes having
an equal aggregate principal amount.

             (h) All Notes issued upon any transfer or exchange of Notes shall
be valid obligations of the Company, evidencing the same debt, and entitled to
the same benefits under this Indenture, as the Notes surrendered upon such
transfer or exchange.

             SECTION 2.08. Special Transfer Provisions. Unless and until a Note
is exchanged for an Exchange Note in connection with an effective Registration
Statement pursuant to the Registration Rights Agreement, the following
provisions shall apply:

             (a) Transfers to QIBs. The following provisions shall apply with
respect to the registration of any proposed transfer of a Certificated Note or
an interest in a Global Note to a QIB:

             (i) If the Note to be transferred consists of (x) Certificated
        Notes, the Registrar shall register the transfer if such transfer is
        being made by a proposed transferor who has checked the box provided for
        on the form of Note stating, or has otherwise advised the Company and
        the Registrar in writing, that the sale has been made in compliance with
        the provisions of Rule 144A to a transferee who has signed the
        certification provided for on the form of Note stating, or has otherwise
        advised the Company and the Registrar in writing, that it is purchasing
        the Note for its own account or an account with respect to which it
        exercises sole investment discretion and that it and any such account is
        a QIB within the meaning of Rule 144A, and is aware that the sale to it
        is being made in reliance on Rule 144A and acknowledges that it has
        received such information regarding the Company as it has requested
        pursuant to Rule 144A or has determined not to request such information
        and that it is aware that the transferor is relying upon its foregoing
        representations in order to claim the exemption from registration
        provided by Rule 144A or (y) an interest in a Global Note, the transfer
        of such interest may be effected only through the book-entry system
        maintained by the Depository.

             (ii) If the proposed transferee is an Agent Member, and the Note to
        be transferred consists of Certificated Notes, upon receipt by the
        Registrar of the documents referred to in clause (i) and instructions
        given in accordance with the Depository's and

<PAGE>   38
                                       32

        the Registrar's procedures, the Registrar shall reflect on its books and
        records the date and an increase in the principal amount of such Global
        Note in an amount equal to the principal amount of the Certificated
        Notes to be transferred, and the Trustee shall cancel the Certificated
        Note so transferred.

             (b) Private Placement Legend. Upon the registration of transfer,
exchange or replacement of Notes not bearing the Private Placement Legend, the
Registrar shall deliver Notes that do not bear the Private Placement Legend.
Upon the registration of transfer, exchange or replacement of Notes bearing the
Private Placement Legend, the Registrar shall deliver only Notes that bear the
Private Placement Legend unless either (i) the Private Placement Legend is no
longer required by Section 2.02 or (ii) there is delivered to the Registrar an
Opinion of Counsel reasonably satisfactory to the Company and the Trustee to the
effect that neither such legend nor the related restrictions on transfer are
required in order to maintain compliance with the provisions of the Securities
Act.

             (c) General. By its acceptance of any Note bearing the Private
Placement Legend, each Holder of such a Note acknowledges the restrictions on
transfer of such Note set forth in this Indenture and in the Private Placement
Legend and agrees that it will transfer such Note only as provided in this
Indenture. The Registrar shall not register a transfer of any Note unless such
transfer complies with the restrictions on transfer of such Note set forth in
this Indenture. In connection with any transfer of Notes to an Institutional
Accredited Investor, each Holder agrees by its acceptance of the Notes to
furnish the Registrar or the Company such certifications, legal opinions or
other information as either of them may reasonably require to confirm that such
transfer is being made pursuant to an exemption from, or a transaction not
subject to, the registration requirements of the Securities Act; provided that
the Registrar shall not be required to determine (but may rely on a
determination made by the Company with respect to) the sufficiency of any such
certifications, legal opinions or other information.

             The Registrar shall retain, in accordance with its customary
procedures, copies of all letters, notices and other written communications
received pursuant to Section 2.07 or this Section 2.08. The Company shall have
the right to inspect and make copies of all such letters, notices or other
written communications at any reasonable time upon the giving of reasonable
written notice to the Registrar.

             (d) Transfers to Non-QIB Institutional Accredited Investors. The
following provisions shall apply with respect to the registration of any
proposed transfer of a Note to any Institutional Accredited Investor which is
not a QIB:

             (i) The Registrar shall register the transfer of any Note, whether
        or not such Note bears the Private Placement Legend, if (x) the
        requested transfer is after the time period referred to in Rule 144(k)
        under the Securities Act as in effect with respect to such transfer or
        (y) the proposed transferee has delivered to the Registrar (A) a
        certificate

<PAGE>   39
                                       33

        substantially in the form of Exhibit C hereto and (B) if the aggregate
        principal amount of the Notes being transferred is less than $100,000 at
        the time of such transfer, an Opinion of Counsel acceptable to the
        Company that such transfer is in compliance with the Securities Act.

             (ii) If the proposed transferor is an Agent Member holding a
        beneficial interest in a Global Note, upon receipt by the Registrar and
        the Company of (x) the documents, if any, required by paragraph (i) and
        (y) instructions given in accordance with the Depository's and the
        Registrar's procedures, the Registrar shall reflect on its books and
        records the date and a decrease in the principal amount of such Global
        Note in an amount equal to the principal amount of the beneficial
        interest in the Global Note to be transferred, and the Company shall
        execute, and the Trustee shall authenticate and deliver, one or more
        Certificated Notes of like tenor and amount.

             SECTION 2.09. Replacement Notes. If a mutilated Note is surrendered
to the Trustee or if the Holder claims that the Note has been lost, destroyed or
wrongfully taken, the Company shall issue and the Trustee shall authenticate a
replacement Note of like tenor and principal amount and bearing a number not
contemporaneously outstanding; provided that the requirements of this Section
2.09 and the second paragraph of Section 2.10 are met. If required by the
Trustee or the Company, an indemnity bond must be furnished that is sufficient
in the judgment of both the Trustee and the Company to protect the Company, the
Trustee or any Agent from any loss that any of them may suffer if a Note is
replaced. The Company may charge such Holder for its expenses and the expenses
of the Trustee in replacing a Note. In case any such mutilated, lost, destroyed
or wrongfully taken Note has become or is about to become due and payable, the
Company in its discretion may pay such Note instead of issuing a new Note in
replacement thereof.

             Every replacement Note is an additional obligation of the Company
and shall be entitled to the benefits of this Indenture.

             SECTION 2.10. Outstanding Notes. Notes outstanding at any time are
all Notes that have been authenticated by the Trustee except for those cancelled
by it, those delivered to it for cancellation and those described in this
Section 2.10 as not outstanding.

             If a Note is replaced pursuant to Section 2.09, it ceases to be
outstanding unless and until the Trustee and the Company receive proof
reasonably satisfactory to them that the replaced Note is held by a bona fide
purchaser.

<PAGE>   40
                                       34

             If the Paying Agent (other than the Company or an Affiliate of the
Company) holds on the maturity date or a redemption date money sufficient to pay
all principal, premium, if any, and interest payable on that date with respect
to the Notes (or portions thereof) to be redeemed or payable on that date, then
on and after that date such Notes cease to be outstanding and interest on them
shall cease to accrue.

             A Note does not cease to be outstanding because the Company or one
of its Affiliates holds such Note; provided, however, that, in determining
whether the Holders of the requisite principal amount of the outstanding Notes
have given any request, demand, authorization, direction, notice, consent or
waiver hereunder, Notes owned by the Company or any other obligor upon the Notes
or any Affiliate of the Company or of such other obligor shall be disregarded
and deemed not to be outstanding, except that, in determining whether the
Trustee shall be protected in relying upon any such request, demand,
authorization, direction, notice, consent or waiver, only Notes which a
Responsible Officer of the Trustee knows to be so owned shall be so disregarded.
Notes so owned which have been pledged in good faith may be regarded as
outstanding if the pledgee establishes to the satisfaction of the Trustee the
pledgee's right so to act with respect to such Notes and that the pledgee is not
the Company or any other obligor upon the Notes or any Affiliate of the Company
or of such other obligor.

             SECTION 2.11. Temporary Notes. Until definitive Notes are ready for
delivery, the Company may prepare and the Trustee shall authenticate temporary
Notes. Temporary Notes shall be substantially in the form of definitive Notes
but may have insertions, substitutions, omissions and other variations
determined to be appropriate by the Officers executing the temporary Notes, as
evidenced by their execution of such temporary Notes. If temporary Notes are
issued, the Company will cause definitive Notes to be prepared without
unreasonable delay. After the preparation of definitive Notes, the temporary
Notes shall be exchangeable for definitive Notes upon surrender of the temporary
Notes at the office or agency of the Company designated for such purpose
pursuant to Section 4.02, without charge to the Holder. Upon surrender for
cancellation of any one or more temporary Notes, the Company shall execute and
the Trustee shall authenticate and deliver in exchange therefor a like principal
amount of definitive Notes of authorized denominations. Until so exchanged, the
temporary Notes shall be entitled to the same benefits under this Indenture as
definitive Notes.

             SECTION 2.12. Cancellation. The Company at any time may deliver to
the Trustee for cancellation any Notes previously authenticated and delivered
hereunder which the Company may have acquired in any manner whatsoever, and may
deliver to the Trustee for cancellation any Notes previously authenticated
hereunder which the Company has not issued and sold. The Registrar and the
Paying Agent shall forward to the Trustee any Notes surrendered to them for
registration of transfer, exchange, purchase or payment. The Trustee shall
cancel all Notes surrendered for registration of transfer, exchange, purchase,
payment or cancellation and shall return all such Notes to the Company. The
Company shall not issue Notes to replace Notes it has paid in full or delivered
to the Trustee for cancellation.

<PAGE>   41
                                       35

             SECTION 2.13. CUSIP Numbers. The Company in issuing the Notes may
use "CUSIP," "CINS," or "ISIN" numbers, or common codes (if then generally in
use), as the case may be, in notices of redemption or exchange as a convenience
to Holders; provided that any such notice shall state that no representation is
made as to the correctness of such numbers either as printed on the Notes or as
contained in any notice of redemption or exchange and that reliance may be
placed only on the other identification numbers printed on the Notes. The
Company shall promptly advise the Trustee of any change in the CUSIP, CINS or
ISIN numbers or common codes for the Notes.

             SECTION 2.14. Defaulted Interest. If the Company defaults in a
payment of interest on the Notes, it shall pay, or shall deposit with the Paying
Agent money in immediately available funds sufficient to pay, the defaulted
interest, plus (to the extent lawful) interest on the defaulted interest, to the
Persons who are Holders on a subsequent special record date. A special record
date, as used in this Section 2.14 with respect to the payment of any defaulted
interest, shall mean the 15th day next preceding the date fixed by the Company
for the payment of defaulted interest, whether or not such day is a Business
Day. At least 15 days before the subsequent special record date, the Company
shall mail to each Holder and to the Trustee a notice that states the subsequent
special record date, the payment date and the amount of defaulted interest to be
paid.

             SECTION 2.15. Issuance of Additional Notes. The Company may,
subject to Article Four of this Indenture, issue up to $100,000,000 aggregate
principal amount of additional Notes under this Indenture. The Notes issued on
the Closing Date and any additional Notes subsequently issued shall be treated
as a single class for all purposes under this Indenture.

                                  ARTICLE THREE
                                   REDEMPTION

             SECTION 3.01. Right of Redemption. The Notes may be redeemed at the
election of the Company, in whole or in part, at any time and from time to time
on or after March 15, 2005 and prior to maturity, upon not less than 30 nor more
than 60 days' prior notice mailed by first-class mail to each Holder's last
address as it appears in the Note Register, at the following Redemption Prices
(expressed as percentages of their principal amount), plus accrued interest, to
the Redemption Date if redeemed during the 12-month period commencing on March
15 of the applicable year set forth below:

<TABLE>
<CAPTION>
YEAR                                                            REDEMPTION PRICE
----                                                            ----------------
<S>                                                             <C>
2005........................................................         106.938%
2006........................................................         104.625%
</TABLE>

<PAGE>   42
                                       36

<TABLE>
<S>                                                                  <C>
2007........................................................         102.313%
2008 and thereafter.........................................         100.000%
</TABLE>

             (b) In addition, at any time prior to March 15, 2003, the Company
may, at its option, redeem up to 35% of the aggregate principal amount of the
Notes with the Net Cash Proceeds of one or more sales of Capital Stock (other
than Disqualified Stock) of the Company, at any time or from time to time in
part, at a Redemption Price (expressed as a percentage of the principal amount)
of 113.875% plus accrued interest to the Redemption Date, provided (i) that
Notes representing at least 65% of the principal amount of the Notes initially
issued on the Closing Date remain outstanding immediately after each such
redemption and (ii) that notice of each such redemption is mailed within 60 days
of each such sale of Capital Stock.

             SECTION 3.02. Notices to Trustee. If the Company elects to redeem
Notes pursuant to Section 3.01, it shall notify the Trustee in writing of the
Redemption Date and the principal amount of Notes to be redeemed.

             The Company shall give each notice provided for in this Section
3.02 in an Officers' Certificate at least 45 days before the Redemption Date
(unless a shorter period shall be satisfactory to the Trustee).

             SECTION 3.03. Selection of Notes to Be Redeemed. If less than all
of the Notes are to be redeemed at any time, the Trustee shall select the Notes
to be redeemed in compliance with the requirements of the principal national
securities exchange, if any, on which the Notes are listed or if the Notes are
not listed on a national securities exchange, by lot or by such other method as
the Trustee in its sole discretion shall deem to be fair and appropriate;
provided that no Notes of $1,000 in principal amount or less shall be redeemed
in part.

             The Trustee shall make the selection from the Notes outstanding and
not previously called for redemption. Notes in denominations of $1,000 in
principal amount may only be redeemed in whole. The Trustee may select for
redemption portions (equal to $1,000 in principal amount or any integral
multiple thereof) of Notes that have denominations larger than $1,000 in
principal amount. Provisions of this Indenture that apply to Notes called for
redemption also apply to portions of Notes called for redemption. The Trustee
shall notify the Company and the Registrar promptly in writing of the Notes or
portions of Notes to be called for redemption.

             SECTION 3.04. Notice of Redemption. With respect to any redemption
of Notes pursuant to Section 3.01, at least 30 days but not more than 60 days
before a Redemption Date, the Company, or at the Company's request the Trustee,
shall mail a notice of redemption by first class mail to each Holder whose Notes
are to be redeemed.

             The notice shall identify the Notes to be redeemed and shall state:

<PAGE>   43
                                       37

             (i) the Redemption Date;

             (ii) the Redemption Price;

             (iii) the name and address of the Paying Agent;

             (iv) that Notes called for redemption must be surrendered to the
        Paying Agent in order to collect the Redemption Price;

             (v) that, unless the Company defaults in making the redemption
        payment, interest on Notes (or portions thereof) called for redemption
        ceases to accrue on and after the Redemption Date and the only remaining
        right of the Holders is to receive payment of the Redemption Price plus
        accrued interest to the Redemption Date upon surrender of the Notes to
        the Paying Agent;

             (vi) that, if any Note is being redeemed in part, the portion of
        the principal amount (equal to $1,000 in principal amount or any
        integral multiple thereof) of such Note to be redeemed and that, on and
        after the Redemption Date, upon surrender of such Note, a new Note or
        Notes in principal amount equal to the unredeemed portion thereof, will
        be reissued; and

             (vii) that, if any Note contains a CUSIP, CINS or ISIN number or a
        common code, as provided in Section 2.13, no representation is being
        made as to the correctness of the CUSIP, CINS or ISIN number or the
        common code either as printed on the Notes or as contained in the notice
        of redemption.

At the Company's request (which request may be revoked by the Company at any
time prior to the time at which the Trustee shall have given such notice to the
Holders), made in writing to the Trustee at least 45 days (or such shorter
period as shall be satisfactory to the Trustee) before a Redemption Date, the
Trustee shall give the notice of redemption in the name and at the expense of
the Company. If, however, the Company gives such notice to the Holders, the
Company shall concurrently deliver to the Trustee a copy of such notice of
redemption.

             SECTION 3.05. Effect of Notice of Redemption. Once notice of
redemption is mailed, Notes called for redemption become due and payable on the
Redemption Date and at the Redemption Price. Upon surrender of any Notes to the
Paying Agent, such Notes shall be paid at the Redemption Price, plus accrued
interest, if any, to the Redemption Date. Notice of redemption shall be deemed
to be given when mailed, whether or not the Holder receives the notice. In any
event, failure to give such notice, or any defect therein, shall not affect the
validity of the proceedings for the redemption of Notes held by Holders to whom
such notice was properly given.

<PAGE>   44
                                       38

             SECTION 3.06. Deposit of Redemption Price. On or prior to any
Redemption Date, the Company shall deposit with the Paying Agent by 10:00 a.m.
New York City time (or, if the Company, one of its Subsidiaries or any of their
Affiliates is acting as Paying Agent, shall segregate and hold in trust as
provided in Section 2.05) money sufficient to pay the Redemption Price of and
accrued interest on all Notes to be redeemed on that date other than Notes or
portions thereof called for redemption on that date that have been delivered by
the Company to the Trustee for cancellation.

             SECTION 3.07. Payment of Notes Called for Redemption. If notice of
redemption has been given in the manner provided above, the Notes or portion of
Notes specified in such notice to be redeemed shall become due and payable on
the Redemption Date at the Redemption Price stated therein, together with
accrued interest to such Redemption Date, and on and after such date (unless the
Company shall default in the payment of such Notes at the Redemption Price and
accrued interest to the Redemption Date, in which case the principal, until
paid, shall bear interest from the Redemption Date at the rate prescribed in the
Notes), such Notes shall cease to accrue interest. Upon surrender of any Note
for redemption in accordance with a notice of redemption, such Note shall be
paid and redeemed by the Company at the Redemption Price, together with accrued
interest, if any, to the Redemption Date; provided that installments of interest
whose Stated Maturity is on or prior to the Redemption Date shall be payable to
the Holders registered as such at the close of business on the relevant Regular
Record Date.

             SECTION 3.08. Notes Redeemed in Part. Upon surrender of any Note
that is redeemed in part, the Company shall execute and the Trustee shall
authenticate and deliver to the Holder a new Note equal in principal amount to
the unredeemed portion of such surrendered Note.

                                  ARTICLE FOUR
                                    COVENANTS

             SECTION 4.01. Payment of Notes. The Company shall pay the principal
of, premium, if any, and interest on the Notes on the dates and in the manner
provided in the Notes and this Indenture. An installment of principal, premium,
if any, or interest shall be considered paid on the date due if the Trustee or
Paying Agent (other than the Company, a Subsidiary of the Company, or any
Affiliate of any of them) holds on that date money designated for and sufficient
to pay the installment by the time of day such installment is required to be
received by the Trustee or Paying Agent. If the Company or any Subsidiary of the
Company or any Affiliate of any of them, acts as Paying Agent, an installment of
principal, premium, if any, or interest shall be considered paid on the due date
if the entity acting as Paying Agent complies with the last sentence of Section
2.05. As provided in Section 6.09, upon any bankruptcy or reorganization

<PAGE>   45
                                       39

procedure relative to the Company, the Trustee shall serve as the Paying Agent
and conversion agent, if any, for the Notes.

             The Company shall pay interest on overdue principal, premium, if
any, and interest on overdue installments of interest, to the extent lawful, at
the rate per annum specified in the Notes.

             SECTION 4.02. Maintenance of Office or Agency. The Company will
maintain an office or agency in the Borough of Manhattan, the City of New York,
where Notes may be surrendered for registration of transfer or exchange or for
presentation for payment and where notices and demands to or upon the Company in
respect of the Notes and this Indenture may be served. The Company will give
prompt written notice to the Trustee of the location, and any change in the
location, of such office or agency. If at any time the Company shall fail to
maintain any such required office or agency or shall fail to furnish the Trustee
with the address thereof, such presentations, surrenders, notices and demands
may be made or served at the address of the Trustee set forth in Section 11.02
hereof.

             The Company may also from time to time designate one or more other
offices or agencies (in or outside the City of New York) where the Notes may be
presented or surrendered for any or all such purposes and may from time to time
rescind such designations; provided that no such designation or rescission shall
in any manner relieve the Company of its obligation to maintain an office or
agency in the Borough of Manhattan, the City of New York, for such purposes. The
Company will give prompt written notice to the Trustee of any such designation
or rescission and of any change in the location of any such other office or
agency.

             The Company hereby initially designates the Corporate Trust Office
or the office of an agent of the Trustee, located in the Borough of Manhattan,
the City of New York, which shall initially be located at State Street Bank and
Trust Company, N.A., 61 Broadway, New York, NY 10006 Attention: Corporate Trust
Department, as such office of the Company in accordance with Section 2.04.

             SECTION 4.03. Limitation on the Incurrence of Indebtedness and the
Issuance of Preferred Stock. (a) The Company will not, and will not permit any
of its Restricted Subsidiaries to, directly or indirectly, Incur any
Indebtedness (other than the Notes issued on the Closing Date, the Exchange
Notes issued in the Exchange Offer and other Indebtedness existing on the
Closing Date) and the Company will not issue or Incur any Disqualified Stock and
will not permit any of its Restricted Subsidiaries to issue or Incur any shares
of Preferred Stock; provided, however, that the Company may Incur Indebtedness
or issue or Incur shares of Disqualified Stock and its Restricted Subsidiaries
may Incur Acquired Indebtedness or Acquired Preferred Stock if, after giving
effect to the Incurrence of such Indebtedness and the receipt and application of
the proceeds therefrom, the Consolidated Leverage Ratio would be greater than
zero and less than 6:1.

<PAGE>   46
                                       40

             Notwithstanding the foregoing, the Company and any Restricted
Subsidiary (except as specified below) may Incur each and all of the following:

             (i) Indebtedness of the Company or any Restricted Subsidiary
        Incurred under one or more Credit Facilities outstanding at any time in
        an aggregate principal amount (together with refinancings thereof) not
        to exceed $200.0 million, less any amount of such Indebtedness
        permanently repaid as provided under Section 4.11.

             (ii) Indebtedness owed:

                    (A) to the Company evidenced by an unsubordinated promissory
             note or

                    (B) to any Restricted Subsidiary; provided that

                         (x) any event which results in any such Restricted
                    Subsidiary ceasing to be a Restricted Subsidiary or any
                    subsequent transfer of such Indebtedness (other than to the
                    Company or another Restricted Subsidiary) shall be deemed,
                    in each case, to constitute an Incurrence of such
                    Indebtedness not permitted by this clause (2)(B) and

                         (y) if the Company is the obligor on such Indebtedness,
                    such Indebtedness must be unsecured and expressly
                    subordinated in right of payment to the Notes;

             (iii) Indebtedness issued in exchange for, or the net proceeds of
        which are used to refinance or refund, then outstanding Indebtedness of
        the Company or any of its Restricted Subsidiaries (other than
        Indebtedness Incurred under clause (i), (ii), (v), (vi), (viii) or (x)
        of this Section 4.03(a)) and any refinancings thereof in an amount not
        to exceed the amount so refinanced or refunded (plus premiums, accrued
        interest, fees and expenses); provided that

                    (A) Indebtedness the proceeds of which are used to refinance
             or refund the Notes or indebtedness that is pari passu with, or
             subordinated in right of payment to, the Notes shall only be
             permitted under this clause (iii) if

                         (x) in case the Notes are refinanced in part or the
                    Indebtedness to be refinanced is pari passu with the Notes,
                    such new Indebtedness, by its terms or by the terms of any
                    agreement or instrument pursuant to which such new
                    Indebtedness is outstanding, is expressly made pari passu
                    with, or subordinate in right of payment to, the remaining
                    Notes, or

<PAGE>   47
                                       41

                         (y) in case the Indebtedness to be refinanced is
                    subordinated in right of payment to the Notes, such new
                    Indebtedness, by its terms or by the terms of any agreement
                    or instrument pursuant to which such new Indebtedness is
                    issued or remains outstanding, is expressly made subordinate
                    in right of payment to the Notes at least to the extent that
                    the Indebtedness to be refinanced is subordinated to the
                    Notes,

                    (B) such new Indebtedness, determined as of the date of
             Incurrence of such new Indebtedness, does not have a final maturity
             prior to the final maturity of the Indebtedness to be refinanced or
             refunded, and the Average Life of such new Indebtedness is at least
             equal to the remaining Average Life of the Indebtedness to be
             refinanced or refunded, and

                    (C) if the Company is the obligor on the Indebtedness to be
             refinanced or refunded, such new Indebtedness shall not be Incurred
             by a Restricted Subsidiary;

             (iv) Indebtedness of the Company to the extent the net proceeds
        thereof are promptly

                    (A) used to purchase Notes tendered in an Offer to Purchase
             made as a result of a Change in Control or

                    (B) deposited to defease the Notes as described under
             "Defeasance";

             (v) Guarantees of the Notes, if any, and Guarantees of Indebtedness
        of the Company by any Restricted Subsidiary provided the Guarantee of
        such Indebtedness is permitted by and made in accordance with Section
        4.07; and

             (vi) Indebtedness,

                    (A) in respect of performance, surety or appeals bonds or
             security deposits provided in the ordinary course of business,

                    (B) under Currency Agreements, Commodity Agreements and
             Interest Rate Agreements; provided that such agreements,

                         (i) are entered into for the primary purpose of
                    protecting the Company or any of its Restricted Subsidiaries
                    against fluctuations in foreign currency exchange rates or
                    interest rates and

<PAGE>   48
                                       42

                         (ii) do not increase the Indebtedness of the obligor
                    outstanding at any time other than as a result of
                    fluctuations in foreign currency exchange rates or interest
                    rates or by reason of fees, indemnities and compensation
                    payable thereunder, and

                    (C) arising from agreements providing for indemnification,
             adjustment of purchase price or similar obligations, or from
             Guarantees or letters of credit, surety bonds or performance bonds
             securing any obligations of the Company or any of its Restricted
             Subsidiaries pursuant to such agreements, in any case Incurred in
             connection with the disposition of any business, assets or
             Restricted Subsidiary (other than Guarantees of Indebtedness
             Incurred by any Person acquiring all or any portion of such
             business, assets or Restricted Subsidiary for the purpose of
             financing such acquisition), in a principal amount not to exceed
             the gross proceeds actually received by the Company or any
             Restricted Subsidiary in connection with such disposition;

             (vii) Indebtedness Incurred to finance the purchase, construction
        or other acquisition after the Closing Date of any property, inventory,
        asset or business directly or indirectly, by the Company or any
        Restricted Subsidiary used in, or to be used in, a Permitted Business;

             (viii) Indebtedness of the Company not to exceed, at any time
        outstanding, two times the Net Cash Proceeds received by the Company
        after the Closing Date from the issuance and sale of its Capital Stock
        (other than Disqualified Stock) to a Person that is not a Subsidiary of
        the Company, to the extent that the Net Cash Proceeds have not been used
        pursuant to clause (C)(ii) of part (a) or clause (iii), (iv) or (vi) of
        part (b) of Section 4.04 to make a Restricted Payment; provided that
        such Indebtedness does not have a final maturity date prior to the final
        maturity date of the Notes and has an Average Life longer than the
        Average Life of the Notes;

             (ix) Indebtedness Incurred for the purpose of paying interest on
        outstanding Indebtedness in the form of additional Indebtedness with the
        same terms, and Disqualified Stock or Preferred Stock Issued for the
        purpose of paying dividends on Disqualified Stock or Preferred Stock in
        the form of additional shares of the same class of Disqualified Stock or
        Preferred Stock, as the case may be; and

             (x) Indebtedness of the Company or any Restricted Subsidiary (in
        addition to Indebtedness permitted under clauses (i) through (ix) above)
        in an aggregate principal amount outstanding at any time (together with
        refinancings thereof) not to exceed $25.0 million, less any amount of
        such Indebtedness permanently repaid as provided under Section 4.11.

<PAGE>   49
                                       43

             (b) Notwithstanding any other provision of this Section 4.03, the
maximum amount of Indebtedness that may be Incurred pursuant to this Section
4.03 will not be deemed to be exceeded, with respect to any outstanding
Indebtedness due solely to the result of fluctuations in the exchange rates of
currencies.

             (c) For purposes of determining any particular amount of
Indebtedness under this Section 4.03,

             (1) Guarantees, Liens or obligations with respect to letters of
        credit supporting Indebtedness otherwise included in the determination
        of such particular amount shall not be included and

             (2) any Liens granted pursuant to the equal and ratable provisions
        referred to in Section 4.09 shall not be treated as Indebtedness.

             For purposes of determining compliance with this Section 4.03, in
the event that an item of Indebtedness meets the criteria of more than one of
the types of Indebtedness described above, including under the first part (a) of
this covenant, the Company, in its sole discretion, shall classify, and from
time to time may reclassify, such item of Indebtedness.

             SECTION 4.04. Limitation on Restricted Payments. The Company will
not, and will not permit any Restricted Subsidiary to

             (i) declare or pay any dividend or make any distribution on or with
        respect to its Capital Stock (other than (1) dividends or distributions
        payable solely in shares of its Capital Stock (other than Disqualified
        Stock) or in options, warrants or other rights to acquire shares of such
        Capital Stock and (2) pro rata dividends or distributions on Common
        Stock of Restricted Subsidiaries held by minority stockholders) held by
        Persons other than the Company or any of its Restricted Subsidiaries,

             (ii) purchase, call for redemption or redeem, retire or otherwise
        acquire for value any shares of Capital Stock of the Company or any
        Restricted Subsidiary of the Company (including options, warrants or
        other rights to acquire such shares of Capital Stock) held by any Person
        other than the Company or any of its Restricted Subsidiaries,

             (iii) make any voluntary or optional principal payment, or
        voluntary or optional redemption, repurchase, defeasance, or other
        acquisition or retirement for value, of Indebtedness of the Company that
        is subordinated in right of payment to the Notes or

             (iv) make any Investment other than a Permitted Investment, in any
        Person (such payments or any other actions described in clauses (i)
        through (iv) above being collectively "Restricted Payments")

<PAGE>   50
                                       44

        if, at the time of, and after giving effect to, the proposed Restricted
        Payment: (A) a Default or Event of Default shall have occurred and be
        continuing, (B) the Company could not Incur at least $1.00 of
        Indebtedness under clause (i) of Section 4.03 hereof or (C) the
        aggregate amount of all Restricted Payments made after the Closing Date
        shall exceed the sum of:

                  (i) the amount of the Company's cumulative Consolidated EBITDA
             less 150% of Consolidated Interest Expense, during the period
             (taken as one accounting period) beginning on the first day of the
             fiscal quarter immediately following the Closing Date and ending on
             the last day of the last fiscal quarter preceding the Transaction
             Date for which reports have been filed with the SEC or provided to
             the Trustee pursuant to Section 4.19, plus

                  (ii) the aggregate Net Cash Proceeds received by the Company
             after the Closing Date from the issuance and sale permitted by this
             Indenture of its Capital Stock (other than Disqualified Stock) to a
             Person who is not a Subsidiary of the Company, including an
             issuance or sale permitted by this Indenture of Indebtedness or
             Disqualified Stock of the Company for cash subsequent to the
             Closing Date upon the conversion of such Indebtedness or
             Disqualified Stock into, or upon the exchange of such Indebtedness
             or Disqualified Stock for, Capital Stock (other than Disqualified
             Stock) of the Company, or from the issuance to a Person who is not
             a Subsidiary of the Company of any options, warrants or other
             rights to acquire Capital Stock of the Company (in each case,
             exclusive of any Disqualified Stock or any options, warrants or
             other rights that are redeemable at the option of the holder, or
             are required to be redeemed, prior to the final maturity of the
             Notes), in each case except to the extent such Net Cash Proceeds
             are used to Incur Indebtedness pursuant to clause (8) of the second
             paragraph of part (a) of Section 4.03, which is outstanding on the
             Transaction Date or used to make a Restricted Payment pursuant to
             clause (6) of paragraph (b) of this Section 4.04, plus

                  (iii) an amount equal to the net reduction in Investments
             (other than reductions in Permitted Investments) in any Person
             resulting from payments of interest on Indebtedness, dividends,
             repayments of loans or advances, or other transfers of assets, in
             each case to the Company or any Restricted Subsidiary or from the
             Net Cash Proceeds from the sale to any Person who is not a
             Subsidiary of the Company of any such Investment (except, in each
             case, to the extent any such payment or proceeds are included in
             the calculation of Consolidated EBITDA), or from redesignations of
             Unrestricted Subsidiaries as Restricted Subsidiaries (valued in
             each case as provided in the definition of "Investments").

                  The foregoing provision shall not be violated by reason of:

                  (i) the payment of any dividend or redemption of any Capital
             Stock within 60 days after the related date of declaration or call
             for redemption if, at said date of

<PAGE>   51
                                       45

        declaration or call for redemption, such payment or redemption would
        comply with the preceding paragraph (a);

             (ii) the redemption, repurchase, defeasance or other acquisition or
        retirement for value of Indebtedness that is subordinated in right of
        payment to the Notes, including premium, if any, and accrued interest,
        with the proceeds of, or in exchange for, Indebtedness Incurred under
        clause (3) of the second paragraph of part (a) of Section 4.03;

             (iii) the repurchase, redemption or other acquisition of Capital
        Stock of the Company (or options, warrants or other rights to acquire
        such Capital Stock) in exchange for, or out of the proceeds of a
        substantially concurrent offering of, shares of Capital Stock (other
        than Disqualified Stock) of the Company (or options, warrants or other
        rights to acquire such Capital Stock); provided that such options,
        warrants or other rights are not redeemable prior to the Stated Maturity
        of the Notes;

             (iv) the making of any principal payment or the repurchase,
        redemption, retirement, defeasance or other acquisition for value of
        Indebtedness which is subordinated in right of payment to the Notes in
        exchange for, or in connection with the conversion of such Indebtedness
        for, or out of the proceeds of, a substantially concurrent offering of,
        shares of the Capital Stock (other than Disqualified Stock) of the
        Company (or options, warrants or other rights to acquire such Capital
        Stock); provided that such options, warrants or other rights are not
        redeemable prior to the Stated Maturity of the Notes;

             (v) payments or distributions, to dissenting stockholders pursuant
        to applicable law, pursuant to or in connection with a consolidation,
        merger or transfer of assets that complies with the provisions of this
        Indenture applicable to mergers, consolidations and transfers of all or
        substantially all of the property and assets of the Company;

             (vi) Investments acquired in exchange for, or out of the proceeds
        of an offering (that occurred within six months at the time of any such
        Investment) of, Capital Stock (other than Disqualified Stock) of the
        Company, to the extent that such proceeds have not been used to make
        Restricted Payment pursuant to clause (iii) or (iv) of this paragraph
        (b) or clause (C)(ii) of paragraph (a) of this Section 4.04 or to Incur
        Indebtedness pursuant to clause (viii) of the second paragraph of part
        (a) of Section 4.03.

             (vii) (a) the redemption, repurchase, retirement or other
        acquisition of any Capital Stock of the Company (or options, warrants or
        other rights to acquire such Capital Stock) from an employee or former
        employee of the Company or any of its Subsidiaries (or from such
        person's estate, heirs or representatives) in connection with such

<PAGE>   52
                                       46

        employee's death, disability or termination of employment, provided that
        the aggregate amount expended pursuant to this clause (vii) (a) does not
        exceed $5.0 million; or

             (b) the redemption, repurchase, retirement or other acquisition of
        any unvested shares of any Capital Stock of the Company (or any unvested
        options, warrants or other rights to acquire such Capital Stock) from an
        employee or former employee of the Company or any of its Subsidiaries
        (or from such person's estate, heirs or representatives) in connection
        with such employee's death, disability or termination of employment, at
        a price per share of Capital Stock not to exceed the price per share at
        which the shares of Capital Stock (or options, warrants or other rights
        to acquire such Capital Stock) were issued or granted to such employee;

             (viii) the payment of dividends on shares of Disqualified Stock of
        the Company or shares of Preferred Stock of the Company's Restricted
        Subsidiaries issued or Incurred in accordance with Section 4.03;

             (ix) the making of any payment on or with respect to, or
        repurchase, redemption, defeasance or acquisition or retirement for
        value, of Convertible Notes in connection with (i) an optional
        redemption of Convertible Notes pursuant to the terms thereof if at the
        time the Company sends a notice of redemption to the holders of such
        Convertible Notes, the Closing Price of the Capital Stock into which
        such Convertible Notes are convertible is greater than the conversion
        price, or (ii) the honoring by the Company of any conversion request by
        a holder of Convertible Notes (including the payment by the Company of
        any cash in lieu of issuing fractional shares) in accordance with the
        terms of Convertible Notes:

             (x) the repurchase of Capital Stock or any options, warrants or
        other rights to acquire Capital Stock of the Company that may be deemed
        to occur upon the cash-less exercise thereof or the payment by the
        Company of any cash in lieu of issuing fractional shares of Capital
        Stock pursuant to the terms of any such options, warrants or other
        rights;

             (xi) other Restricted Payments in an aggregate amount not to exceed
        $20.0 million;

provided that, except in the case of clauses (i) and (iii), no Default or Event
of Default shall have occurred and be continuing or occur as a consequence of
the actions or payments set forth therein.

             (c) Each Restricted Payment permitted pursuant to the preceding
part (b) (other than the Restricted Payment referred to in clause (ii) or (x)
thereof, an exchange of capital Stock for Capital Stock or Indebtedness referred
to in clause (iii) or (iv) thereof and an
<PAGE>   53
                                       47

Investment acquired in exchange for Capital Stock referred to in clause (vi)
thereof), and the Net Cash Proceeds from any issuance of Capital Stock referred
to in clauses (iii), (iv) and (vi), shall be included in calculating whether the
conditions of clause (C) of part (a) of this Section 4.04 have been met with
respect to any subsequent Restricted Payments.

             For purposes of determining compliance with this Section 4.04:

             (i) the amount of all Restricted Payments (other than cash) shall
        be the fair market value on the date of the Restricted Payment of the
        asset(s) or securities proposed to be transferred or issued by the
        Company (or such Restricted Subsidiary, as the case may be) pursuant to
        the Restricted Payment;

             (ii) the fair market value of any asset(s) or securities that are
        required to be valued by this covenant shall be determined in good faith
        by the Board of Directors; provided that such determination shall be
        supported by the opinion or appraisal of an accounting, appraisal or
        investment banking firm of national standing if such fair market value
        would in the good faith determination of the Board of Directors exceed
        $10 million;

             (iii) in the event that a Restricted Payment meets the criteria of
        more than one of the types of Restricted Payments described in the above
        clauses, including part (a) of this Section 4.04, the Company, in its
        sole discretion, may order and classify, and from time to time may
        reclassify, such Restricted Payment if it would have been permitted at
        the time such Restricted Payment was made and at the time of such
        reclassification; and

             (iv) The amount of any Investment "outstanding" at any time shall
        be deemed to be equal to the fair market value of such Investment on the
        date made, less the return of capital, repayment of loans, return on
        capital and release of Guarantees, in each case of or to the Company and
        its Restricted Subsidiaries with respect to such Investment (up to the
        amount of such Investment on the date made).

             SECTION 4.05. Limitation on Dividend and Other Payment Restrictions
Affecting Restricted Subsidiaries. (a) The Company will not, and will not permit
any Restricted Subsidiary to create or otherwise cause or suffer to exist or
become effective any consensual encumbrance or restriction of any kind on the
ability of any Restricted Subsidiary to:

             (1) pay dividends or make any other distributions permitted by
        applicable law on any Capital Stock of such Restricted Subsidiary owned
        by the Company or any other Restricted Subsidiary,

             (2) pay any Indebtedness owed to the Company or any other
        Restricted Subsidiary,

<PAGE>   54
                                       48

             (3) make loans or advances to the Company or any other Restricted
        Subsidiary or

             (4) transfer any of its property or assets to the Company or any
        other Restricted Subsidiary.

             (b) The foregoing provisions shall not restrict any encumbrances or
restrictions:

             (i) existing on the Closing Date in this Indenture or any other
        agreements in effect on the Closing Date, and any extensions,
        refinancings, renewals or replacements of such agreements; provided that
        the encumbrances and restrictions in any such extensions, refinancings,
        renewals or replacements taken as a whole are no less favorable in any
        material respect to the Holders of the Notes than those encumbrances or
        restrictions that are then in effect and that are being extended,
        refinanced, renewed or replaced;

             (ii) existing under or by reason of applicable law;

             (iii) existing with respect to any Person or the property or assets
        of such Person acquired by the Company or any Restricted Subsidiary,
        existing at the time of such acquisition and not incurred in
        contemplation thereof, which encumbrances or restrictions are not
        applicable to any Person or the property or assets of any Person other
        than such Person or the property or asset of such Person so acquired;

             (iv) in the case of clause (4) of part (a) of this Section 4.05,
        (A) that restrict in a customary manner the subletting, assignment or
        transfer of any property or asset that is a lease, license, conveyance
        or contract or similar property or asset, (B) existing by virtue of any
        transfer of, agreement to transfer, option or right with respect to, or
        Lien on, any property or assets of the Company or any Restricted
        Subsidiary not otherwise prohibited by this Indenture or (C) arising or
        agreed to in the ordinary course of business, not relating to any
        Indebtedness, and that do not, individually or in the aggregate, detract
        from the value of property or assets of the Company or any Restricted
        Subsidiary in any manner material to the Company or any Restricted
        Subsidiary;

             (v) with respect to a Restricted Subsidiary and imposed pursuant to
        an agreement that has been entered into for the sale or disposition of
        all or substantially all of the Capital Stock of, or property and assets
        of, such Restricted Subsidiary;

             (vi) contained in the terms of any Indebtedness or any agreement
        pursuant to which such Indebtedness was issued if:

<PAGE>   55
                                       49

                    (A) the encumbrance or restriction applies only in the event
             of a payment default or a default with respect to a financial
             covenant contained in any Indebtedness or agreement,

                    (B) the encumbrance or restriction is not materially more
             disadvantageous to the Holders of the Notes than is customary in
             comparable financings (as determined by the Company in good faith)
             and

                    (C) the Company determines that any such encumbrance or
             restriction will not materially affect the Company's ability to
             make principal or interest payments on the Notes; or

             (vii) contained in the terms of any Indebtedness of any Restricted
        Subsidiary of the Company that is a Foreign Subsidiary or any agreement
        pursuant to which such Indebtedness was issued if:

                    (A) the encumbrance or restriction is not materially more
             disadvantageous to the Holders of the Notes than is customary in
             comparable financings (as determined by the Company in good faith)
             and

                    (B) the Company determines that any such encumbrance or
             restriction will not materially affect the Company's ability to
             make principal or interest payments on the Notes; or

             (viii) restrictions or encumbrances imposed at the request of joint
        venture partners, provided that such joint venture is engaged in a
        Permitted Business.

Nothing contained in this Section 4.05 shall prevent the Company or any of its
Restricted Subsidiaries from (1) creating, incurring, assuming or suffering to
exist any Liens otherwise permitted in Section 4.09 or (2) restricting the sale
or other disposition of property or assets of the Company or any of its
Restricted Subsidiaries that secure Indebtedness of the Company or any of its
Restricted Subsidiaries.

             SECTION 4.06. Limitation on the Issuance and Sale of Capital Stock
of Restricted Subsidiaries. The Company will not sell, and will not permit any
Restricted Subsidiary to issue or sell, any shares of Capital Stock of a
Restricted Subsidiary (including options, warrants or other rights to purchase
shares of such Capital Stock) except (i) to the Company or a Restricted
Subsidiary of the Company; (ii) issuances of director's qualifying shares or
sales to foreign nationals of shares of Capital Stock of foreign Restricted
Subsidiaries, to the extent required by applicable law; (iii) if, immediately
after giving effect to such issuance or sale, such Restricted Subsidiary would
no longer constitute a Restricted Subsidiary and any Investment in such Person
remaining after giving effect to such issuance or sale would have been permitted
to be made under Section 4.04 hereof if made on the date of such issuance or
sale;

<PAGE>   56
                                       50

(iv) sales or issuances of Common Stock (including options, warrants or other
rights to purchase shares of such Common Stock) of a Restricted Subsidiary by
the Company or a Restricted Subsidiary, provided that such sale complies with
Section 4.11; or (v) Issuances of Preferred Stock made in accordance with
Section 4.03.

             SECTION 4.07. Limitation on Issuances of Guarantees by Restricted
Subsidiaries. The Company will not permit any Restricted Subsidiary to Guarantee
any Indebtedness of the Company which is equal in right of payment with or
subordinate in right of payment to the Notes ("Guaranteed Indebtedness"), unless

             (1) such Restricted Subsidiary simultaneously executes and delivers
        a supplemental indenture to this Indenture providing for a Guarantee (a
        "Note Guarantee") of payment of the Notes by such Restricted Subsidiary
        and

             (2) such Restricted Subsidiary waives, and will not in any manner
        whatsoever claim or take the benefit or advantage of, any rights of
        reimbursement, indemnity or subrogation or any other rights against the
        Company or any other Restricted Subsidiary as a result of any payment by
        such Restricted Subsidiary under its Note Guarantee;

provided that this paragraph shall not be applicable to (i) any Guarantee of any
Restricted Subsidiary that existed at the time such Person became a Restricted
Subsidiary and was not Incurred in connection with, or in contemplation of, such
Person becoming a Restricted Subsidiary or (ii) any Guarantee of Indebtedness of
the Company which Indebtedness would have been permitted to be Incurred by a
Restricted Subsidiary pursuant to Section 4.03.

        If the Guaranteed Indebtedness is

             (A) equal in right of payment with the Notes, then the Guarantee of
        such Guaranteed Indebtedness shall be equal in right of payment with, or
        subordinated to, the Note Guarantee or

             (B) subordinated to the Notes, then the Guarantee of such
        Guaranteed Indebtedness shall be subordinated to the Note Guarantee at
        least to the extent that the Guaranteed Indebtedness is subordinated to
        the Notes.

             Notwithstanding the foregoing, any Note Guarantee by a Restricted
Subsidiary may provide by its terms that it shall be automatically and
unconditionally released and discharged upon:

             (1) any sale, exchange or transfer, to any Person not an Affiliate
        of the Company, of all of the Company's and each Restricted Subsidiary's
        Capital Stock in, or

<PAGE>   57
                                       51

        all or substantially all the assets of, such Restricted Subsidiary
        (which sale, exchange or transfer is not prohibited by this Indenture);

             (2) the release or discharge of the Guarantee which resulted in the
        creation of such Note Guarantee, except a discharge or release by or as
        a result of payment under such Guarantee; or

             (3) upon the designation of such Restricted Subsidiary as an
        Unrestricted Subsidiary in accordance with the terms of this Indenture.

             SECTION 4.08. Limitation on Transactions with Affiliates. The
Company will not, and will not permit any Restricted Subsidiary to, enter into,
renew or extend any transaction (including, without limitation, the purchase,
sale, lease or exchange of property or assets, or the rendering of any service)
with, or for the benefit of, any Affiliate of the Company or any Restricted
Subsidiary, except upon fair and reasonable terms no less favorable to the
Company or such Restricted Subsidiary than could be obtained, at the time of
such transaction or, if such transaction is pursuant to a written agreement, at
the time of the execution of the agreement providing therefor, in a comparable
arm's-length transaction with a Person that is not such an Affiliate.

             The foregoing limitation does not limit, and shall not apply to:

             (i) transactions (A) approved by a majority of the disinterested
        members of the Board of Directors or (B) for which the Company or a
        Restricted Subsidiary delivers to the Trustee a written opinion of a
        nationally recognized investment banking, accounting, valuation or
        appraisal firm stating that the transaction is fair to the Company or
        such Restricted Subsidiary from a financial point of view;

             (ii) any transaction solely between the Company and any of its
        Restricted Subsidiaries or solely among Restricted Subsidiaries;

             (iii) the payment of reasonable and customary regular fees to
        officers and directors of the Company and indemnification arrangements
        entered into by the Company in the ordinary course of business and
        consistent with past practices of the Company;

             (iv) any payments or other transactions pursuant to any tax-sharing
        agreement between the Company and any other Person with which the
        Company files a consolidated tax return or with which the Company is
        part of a consolidated group for tax purposes;

             (v) any sale of shares of Capital Stock (other than Disqualified
        Stock) of the Company; or

<PAGE>   58
                                       52

             (vi) any Permitted Investments or any Restricted Payments not
        prohibited by Section 4.04.

Notwithstanding the foregoing, any transaction or series of related transactions
covered by the first paragraph of this Section 4.08 and not covered by clauses
(ii) through (iv) of this paragraph, (a) the aggregate amount of which exceeds
$5 million in value, must be approved or determined to be fair in the manner
provided for in clause (i)(A) or (B) above and (b) the aggregate amount of which
exceeds $10 million in value, must be determined to be fair in the manner
provided for in clause (i) (B) above.

             SECTION 4.09. Limitation on Liens. The Company will not, and will
not permit any Restricted Subsidiary to, create, Incur, assume or suffer to
exist any Lien securing Indebtedness on any of its assets or properties of any
character, or any shares of Capital Stock or Indebtedness of any Restricted
Subsidiary, without making effective provision for all of the Notes and all
other amounts due under this Indenture to be directly secured equally and
ratably with (or, if the obligation or liability to be secured by such Lien is
subordinated in right of payment to the Notes, prior to) the obligation or
liability secured by such Lien.

             The foregoing limitation does not apply to:

             (i) Liens existing on the Closing Date;

             (ii) Liens granted after the Closing Date on any assets or Capital
        Stock of the Company or its Restricted Subsidiaries created in favor of
        the Holders of the Notes, the Exchange Notes or any Additional Notes;

             (iii) Liens with respect to the assets of a Restricted Subsidiary
        granted by such Restricted Subsidiary to the Company or another
        Restricted Subsidiary to secure Indebtedness owing to the Company or
        such other Restricted Subsidiary or the Guarantee of any such
        Indebtedness;

             (iv) Liens securing Indebtedness, which is permitted to be Incurred
        under clause (iii) of the second paragraph of part (a) of Section 4.03
        hereof which is Incurred to refinance secured Indebtedness; provided
        that such Liens do not extend to or cover any property or assets of the
        Company or any Restricted Subsidiary other than the property or assets
        securing the Indebtedness being refinanced;

             (v) Liens securing Indebtedness Incurred under clause (i) of the
        second paragraph of part (a) of Section 4.03; provided that such Liens
        only cover property or assets of the obligor, co-obligor or guarantor of
        such Indebtedness;

<PAGE>   59
                                       53

             (vi) Liens on cash set aside at the time of the Incurrence of any
        Indebtedness, or government securities or Temporary Cash Investments
        purchased with such cash, in either case, to the extent that such cash,
        government securities or Temporary Cash Investments pre-fund the payment
        of interest on such Indebtedness and are held in a collateral or escrow
        account or similar arrangement to be applied to pay such interest when
        due;

             (vii) Liens arising under the Existing Vendor Finance Agreements as
        in effect on the Closing Date;

             (viii) Liens on the assets or property of any Restricted Subsidiary
        of the Company that is a Foreign Subsidiary securing Indebtedness which
        is permitted to be Incurred by such Restricted Subsidiary under this
        Indenture;

             (ix) Liens securing Indebtedness not to exceed at any one time
        outstanding in the aggregate $1.0 million; or

             (x) Permitted Liens.

             SECTION 4.10. Limitation on Sale-Leaseback Transactions. The
Company will not, and will not permit any Restricted Subsidiary to, enter into
any sale-leaseback transaction involving any of its assets or properties whether
now owned or hereafter acquired, whereby the Company or a Restricted Subsidiary
sells or transfers such assets or properties and then or thereafter leases such
assets or properties or any part thereof or any other assets or properties which
the Company or such Restricted Subsidiary, as the case may be, intends to use
for substantially the same purpose or purposes as the assets or properties sold
or transferred.

             The foregoing restriction does not apply to any sale-leaseback
        transaction if:

             (i) the lease is for a period, including renewal rights, of not in
        excess of three years;

             (ii) the lease secures or relates to industrial revenue or
        pollution control bonds;

             (iii) the transaction is solely between the Company and any
        Restricted Subsidiary or solely between Restricted Subsidiaries; or

             (iv) such sale-leaseback transaction complies with Section 4.11.

             SECTION 4.11. Limitation on Asset Sales. The Company will not, and
will not permit any Restricted Subsidiary to, consummate any Asset Sale, unless:

<PAGE>   60
                                       54

             (i) the consideration received by the Company or such Restricted
        Subsidiary is at least equal to the fair market value (as determined in
        good faith by the Board of Directors (including as to the value of all
        noncash consideration) and, if determined to be in excess of $5.0
        million, as set forth in an Officers' Certificate delivered to the
        Trustee) of the assets sold or disposed of (or of the Capital Stock
        issued, sold or otherwise disposed of);

             (ii) at least 75% of the consideration received consists of:

                    (A) cash or Temporary Cash Investments,

                    (B) the assumption, payment or extinguishment of
             Indebtedness or other liabilities, in each case not subordinated in
             right of payment to the Notes, of the Company or any Restricted
             Subsidiary (in each case, other than Indebtedness owed to the
             Company or any Restricted Subsidiary), provided that the Company or
             such Restricted Subsidiary is irrevocably and unconditionally
             released from all liability under such Indebtedness or other
             liabilities, or

                    (C) Replacement Assets; and

             (iii) (I) the Net Cash Proceeds received by the Company (or such
        Restricted Subsidiary, as the case may be) from such Asset Sale are
        applied within 365 days following the receipt of such Net Cash Proceeds,
        to the extent the Company (or such Restricted Subsidiary, as the case
        may be) elects:

                    (A) apply an amount equal to such excess Net Cash Proceeds
             to permanently repay unsubordinated Indebtedness of the Company or
             Indebtedness of any other Restricted Subsidiary, in each case owing
             to a Person other than the Company or any of its Restricted
             Subsidiaries, or

                    (B) invest an equal amount, or the amount not so applied
             pursuant to clause (A) (or enter into a definitive agreement
             committing to so invest within 365 days after the date of such
             agreement), in Replacement Assets, or

        (II) apply such Net Cash Proceeds, to the extent not applied pursuant to
        clause (iii)(I), as provided in the following paragraphs of this Section
        4.11.

The amount of such excess Net Cash Proceeds required to be applied (or to be
committed to be applied) during such 365-day period as set forth in clause
(iii)(I) of the preceding sentence and not applied as so required by the end of
such period shall constitute "Excess Proceeds".

<PAGE>   61
                                       55

             If, as of the first day of any calendar month, the aggregate amount
of Excess Proceeds not theretofore subject to an Offer to Purchase pursuant to
this Section 4.11 totals at least $10 million, the Company must commence, not
later than the fifteenth Business Day of such month, and consummate an Offer to
Purchase from the Holders of the Notes (and if required by the terms of any
Indebtedness that is equal in right of payment with the Notes ("Pari Passu
Indebtedness"), from the holders of such Pari Passu Indebtedness) on a pro rata
basis an aggregate principal amount of Notes (and Pari Passu Indebtedness) equal
to the Excess Proceeds on such date, at a purchase price equal to 100% of their
principal amount, plus, in each case, accrued interest (if any) to the Payment
Date. To the extent that any Excess Proceeds remain after consummation of an
Asset Sale Offer, the Company may use such Excess Proceeds for any purpose not
otherwise prohibited by this Indenture. If the aggregate principal amount of
Notes and Pari Passu Indebtedness tendered into such Asset Sale Offer
surrendered by holders thereof exceeds the amount of Excess Proceeds, the
Trustee shall select the Notes and Pari Passu Indebtedness to be purchased on a
pro rata basis in proportion to the respective principal amounts (or accreted
values in the case of Indebtedness issued with an original issue discount) of
the Notes and such other Indebtedness. Upon completion of such Asset Sale Offer,
the amount of Excess Proceeds shall be reset at zero for purposes of the first
sentence of this paragraph.

             SECTION 4.12. Repurchase of Notes upon a Change of Control. The
Company must commence, within 60 days of the occurrence of a Change of Control,
and consummate an Offer to Purchase for all the Notes then outstanding, at a
purchase price equal to 101% of the principal amount, plus accrued interest (if
any) to the Payment Date; provided that the Company shall not be obligated to
repurchase Notes pursuant to a Change of Control Offer in the event that it has
exercised its rights to redeem all of the Notes pursuant to this Indenture.

             There can be no assurance that the Company will have sufficient
funds available at the time of any Change of Control to make any debt payment
(including repurchases of Notes) required by the first paragraph of this Section
4.12 or any similar covenant that in other securities of the Company which might
be outstanding at the time).

             The first paragraph of this Section 4.12 requiring the Company to
repurchase the Notes will, unless consents are obtained, require the Company to
repay all indebtedness then outstanding which by its terms would prohibit such
Note repurchase, either prior to or concurrently with such Note repurchase.

             SECTION 4.13. Business Activities. The Company will not, and will
not permit any of its Restricted Subsidiaries to engage, to more than a de
minimus extent, in any business other than a Permitted Business.

             SECTION 4.14. Existence. Except as otherwise provided or permitted
in Articles Four and Five of this Indenture, the Company will do or cause to be
done all things necessary to preserve and keep in full force and effect its
existence and the existence of each of its Restricted

<PAGE>   62
                                       56

Subsidiaries in accordance with the respective organizational documents of the
Company and each such Subsidiary (as the same may be amended from time to time)
and the rights (whether pursuant to charter, partnership certificate, agreement,
statute or otherwise), material licenses and franchises of the Company and each
such Subsidiary; provided that the Company shall not be required to preserve any
such right, license or franchise, or the existence of any Restricted Subsidiary,
if the maintenance or preservation thereof is no longer desirable in the conduct
of the business of the Company and its Restricted Subsidiaries taken as a whole.

             SECTION 4.15. Payment of Taxes and Other Claims. The Company will
pay or discharge and shall cause each of its Subsidiaries to pay or discharge,
or cause to be paid or discharged, before the same shall become delinquent (i)
all material taxes, assessments and governmental charges levied or imposed upon
(a) the Company or any such Subsidiary, (b) the income or profits of any such
Subsidiary which is a corporation or (c) the property of the Company or any such
Subsidiary and (ii) all material lawful claims for labor, materials and supplies
that, if unpaid, might by law become a Lien upon the property of the Company or
any such Subsidiary; provided that the Company shall not be required to pay or
discharge, or cause to be paid or discharged, any such tax, assessment, charge
or claim the amount, applicability or validity of which is being contested in
good faith by appropriate proceedings, for which adequate reserves have been
established.

             SECTION 4.16. Maintenance of Properties and Insurance. The Company
will cause all properties used or useful in the conduct of its business or the
business of any of its Restricted Subsidiaries, to be maintained and kept in
good condition, repair and working order (ordinary wear and tear excepted) and
supplied with all necessary equipment and will cause to be made all necessary
repairs, renewals, replacements, betterments and improvements thereof, all as in
the judgment of the Company may be necessary so that the business carried on in
connection therewith may be properly and advantageously conducted at all times;
provided that nothing in this Section 4.16 shall prevent the Company or any such
Subsidiary from discontinuing the use, operation or maintenance of any of such
properties or disposing of any of them, if such discontinuance or disposal is,
in the judgment of the Company, desirable in the conduct of the business of the
Company or such Subsidiary.

             The Company will provide or cause to be provided, for itself and
its Restricted Subsidiaries, insurance (including appropriate self-insurance)
against loss or damage of the kinds customarily insured against by corporations
similarly situated and owning like properties, with reputable insurers or with
the government of the United States of America, or an agency or instrumentality
thereof, in such amounts, with such deductibles and by such methods as shall be
customary for corporations similarly situated in the industry in which the
Company or such Restricted Subsidiary, as the case may be, is then conducting
business.

             SECTION 4.17. Notice of Defaults. In the event that the Company
becomes aware of any Default or Event of Default, the Company, promptly after it
becomes aware thereof, will give written notice thereof to the Trustee.

<PAGE>   63
                                       57

             SECTION 4.18. Compliance Certificates. The principal accounting
officer and the principal financial officer of the Company shall certify in the
form of an Officer's Certificate delivered to the Trustee, on or before a date
not more than 90 days after the end of each fiscal year of the Company, that a
review has been conducted of the activities of the Company and its Restricted
Subsidiaries and the Company's and its Restricted Subsidiaries' performance
under this Indenture and that the Company has fulfilled all obligations
hereunder, or, if there has been a default in the fulfillment of any such
obligation, specifying each such default and the nature and status thereof. The
Company shall also notify the Trustee of any default or defaults in the
performance of any covenants or agreements under this Indenture. The Company
shall also comply with the other provisions of Section 314(a) of the TIA.

             SECTION 4.19. Commission Reports and Reports to Holders. At all
times from and after the earlier of (i) the date of the commencement of an
Exchange Offer, the effectiveness of a Shelf Registration Statement of the
effectiveness or a registration statement with respect to its Capital Stock (in
either case, a "Registration"), (ii) the date that is six months after the
Closing Date or (iii) in either case, whether or not the Company is then
required to file reports with the Commission, the Company shall file with the
Commission all such reports and other information as it would be required to
file with the Commission by Sections 13(a) or 15(d) under the Securities
Exchange Act of 1934 if it were subject thereto. The Company shall supply the
Trustee and each Holder or shall supply to the Trustee for forwarding to each
such Holder, without cost to such Holder, copies of such reports and other
information. In addition, at all times prior to the earlier of the date of the
Registration and the date that is six months after the Closing Date, the Company
shall, at its cost, deliver to each Holder of the Notes quarterly and annual
reports substantially equivalent to those which would be required by the
Exchange Act. In addition, at all times prior to the Registration, upon the
request of any Holder or any prospective purchaser of the Notes designated by a
Holder, the Company shall supply to such Holder or such prospective purchaser
the information required under Rule 144A under the Securities Act.

             SECTION 4.20. Waiver of Stay, Extension or Usury Laws. The Company
covenants (to the extent that it may lawfully do so) that it will not at any
time insist upon, or plead, or in any manner whatsoever claim or take the
benefit or advantage of, any stay or extension law or any usury law or other law
that would prohibit or forgive the Company from paying all or any portion of the
principal of, premium, if any, or interest on the Notes as contemplated herein,
wherever enacted, now or at any time hereafter in force, or that may affect the
covenants or the performance of this Indenture; and (to the extent that it may
lawfully do so) the Company hereby expressly waives all benefit or advantage of
any such law and covenants that it will not hinder, delay or impede the
execution of any power herein granted to the Trustee, but will suffer and permit
the execution of every such power as though no such law had been enacted.

<PAGE>   64
                                       58

                                  ARTICLE FIVE
                              SUCCESSOR CORPORATION

             SECTION 5.01. When Company May Merge, Etc. The Company shall not
consolidate with, merge with or into, or sell, assign, convey, transfer, lease
or otherwise dispose of all or substantially all of its property and assets (as
an entirety or substantially an entirety in one transaction or a series of
related transactions) to, any Person or permit any Person to merge with or into
the Company unless:

             (i) the Company shall be the continuing Person, or the Person (if
        other than the Company) formed by such consolidation or into which the
        Company is merged or that acquired or leased such property and assets of
        (the "Surviving Person") shall be a corporation organized and validly
        existing under the laws of the United States of America or any
        jurisdiction thereof and shall expressly assume, by a supplemental
        indenture, executed and delivered to the Trustee, all of the obligations
        of the Company under this Indenture and the Notes;

             (ii) no Default or Event of Default shall exist or shall occur
        immediately after giving effect on a pro forma basis to such
        transaction;

             (iii) immediately after giving effect to such transaction on a pro
        forma basis, the Company, or the Surviving Person, as the case may be,
        could Incur at least $1.00 of Indebtedness under the first paragraph of
        Section 4.03 hereof; provided that this clause (iii) shall not apply to
        a consolidation, merger or sale of all (but not less than all) of the
        assets of the Company if all Liens and Indebtedness of the Company or
        the Surviving Person, as the case may be, and its Restricted
        Subsidiaries outstanding immediately after such transaction would have
        been permitted (and all such Liens and Indebtedness, other than Liens
        and Indebtedness of the Company and its Restricted Subsidiaries
        outstanding immediately prior to the transaction, shall be deemed to
        have been Incurred) for all purposes of this Indenture;

             (iv) the Company delivers to the Trustee an Officers' Certificate
        (attaching the arithmetic computations to demonstrate compliance with
        clause (iii) of this Section 5.01) and Opinion of Counsel, in each case
        stating that such consolidation, merger or transfer and such
        supplemental indenture complies with this provision and that all
        conditions precedent provided for herein relating to such transaction
        have been complied with; and

             (v) each Subsidiary Guarantor, if any, unless such Subsidiary
        Guarantor is the Person with which the Company has entered into a
        transaction under this Section 5.01, shall have by amendment to its Note
        Guarantee confirmed that its Note Guarantee shall

<PAGE>   65
                                       59

        apply to the obligations of the Company or the Surviving Person in
        accordance with the Notes and this Indenture;

provided, however, that clause (iii) of this Section 5.01 does not apply if, in
the good faith determination of the Board of Directors of the Company, whose
determination shall be evidenced by a Board Resolution, the principal purpose of
such transaction is to change the state of incorporation of the Company.

             SECTION 5.02. Successor Substituted. Upon any consolidation or
merger, or any sale, conveyance, transfer or other disposition of all or
substantially all of the property and assets of the Company in accordance with
Section 5.01 of this Indenture, the successor Person formed by such
consolidation or into which the Company is merged or to which such sale,
conveyance, transfer or other disposition is made shall succeed to, and be
substituted for, and may exercise every right and power of, the Company under
this Indenture with the same effect as if such successor Person had been named
as the Company herein.

                                   ARTICLE SIX
                              DEFAULT AND REMEDIES

             SECTION 6.01. Events of Default. An "Event of Default" shall occur
with respect to the Notes if:

             (a) default in the payment of principal of (or premium, if any, on)
        any Note when the same becomes due and payable at maturity, upon
        acceleration, redemption or otherwise;

             (b) default in the payment of interest on any Note when the same
        becomes due and payable, and such default continues for a period of 30
        days; provided that a failure to make any of the first four scheduled
        interest payments on the Notes within three business days after an
        interest payment date will constitute an Event of Default with no grace
        or cure period;

             (c) default in the performance or breach of the provisions of this
        Indenture applicable to mergers, consolidations and transfers of all or
        substantially all of the assets of the Company or the failure by the
        Company to make or consummate an Offer to Purchase in accordance with
        Section 4.11 or Section 4.12;

             (d) the Company or any Restricted Subsidiary defaults in the
        performance of or breaches any other covenant or agreement in this
        Indenture or under the Notes (other than a default specified in clause
        (a), (b) or (c) above) and such default or breach

<PAGE>   66
                                       60

        continues for a period of 45 consecutive days after written notice by
        the Trustee or the Holders of 25% or more in aggregate principal amount
        of the Notes;

             (e) the default under any mortgage, indenture or instrument under
        which there may be issued or by which there may be secured or evidenced
        any Indebtedness of the Company or any of its Significant Subsidiaries
        (or the payment of which is Guaranteed by the Company or any of its
        Significant Subsidiaries) whether such Indebtedness or Guarantee now
        exists or is created after the Closing Date, and either such
        Indebtedness is already due and payable or such default results in the
        acceleration of such Indebtedness prior to its express maturity and, in
        each case, the amount of any such Indebtedness, together with the amount
        of any other such Indebtedness the maturity of which has been so
        accelerated or which is already due and payable, aggregates $10 million
        or more;

             (f) one or more judgments, orders or decrees for the payment of
        money in excess of $10 million, individually or in the aggregate (net of
        applicable insurance coverage which is acknowledged in writing by the
        insurer), shall be entered against the Company or any of its Significant
        Subsidiaries or any of their respective properties and shall not be
        discharged and there shall have been a period of 60 days or more during
        which a stay of enforcement of such judgment or order, by reason of
        pending appeal or otherwise, shall not be in effect;

             (g) a court having jurisdiction in the premises enters a decree or
        order for:

                    (i) relief in respect of the Company or any Significant
             Subsidiary in an involuntary case under any applicable bankruptcy,
             insolvency or other similar law now or hereafter in effect,

                    (ii) appointment of a receiver, liquidator, assignee,
             custodian, trustee, sequestrator or similar official of the Company
             or any Significant Subsidiary or for all or substantially all of
             the property and assets of the Company or any Significant
             Subsidiary or

                    (iii) the winding up or liquidation of the affairs of the
             Company or any Significant Subsidiary and, in each case, such
             decree or order shall remain unstayed and in effect for a period of
             45 consecutive days;

             (h) the Company or any Significant Subsidiary (A) commences a
        voluntary case under any applicable bankruptcy, insolvency or other
        similar law now or hereafter in effect, or consents to the entry of an
        order for relief in an involuntary case under any such law, (B) consents
        to the appointment of or taking possession by a receiver, liquidator,
        assignee, custodian, trustee, sequestrator or similar official of the
        Company or any Significant Subsidiary or for all or substantially all of
        the property and assets of the

<PAGE>   67
                                       61

        Company or any Significant Subsidiary or (C) effects any general
        assignment for the benefit of creditors; or

             (i) the Pledge Agreement shall cease to be in full force and effect
        or enforceable in accordance with its terms, other than in accordance
        with its terms.

             SECTION 6.02. Acceleration. If an Event of Default (other than an
Event of Default specified in clause (g) or (h) of Section 6.01 that occurs with
respect to the Company or any Significant Subsidiary) occurs and is continuing
under this Indenture, the Trustee or the Holders of at least 25% in aggregate
principal amount of the Notes then outstanding, by written notice to the Company
(and to the Trustee if such notice is given by the Holders), may, and the
Trustee at the request of such Holders shall, declare the principal amount of,
premium, if any, and accrued interest on the Notes to be immediately due and
payable. Upon a declaration of acceleration, such principal of, premium, if any,
and accrued interest shall be immediately due and payable. In the event of a
declaration of acceleration because an Event of Default set forth in clause (e)
of Section 6.01 has occurred and is continuing, such declaration of acceleration
shall be automatically rescinded and annulled if the event of default triggering
such Event of Default pursuant to clause (e) shall be remedied or cured by the
Company or the relevant Restricted Subsidiary or waived by the holders of the
relevant Indebtedness within 60 days after the declaration of acceleration with
respect thereto. If an Event of Default specified in clause (g) or (h) of
Section 6.01 occurs with respect to the Company or any Significant Subsidiary,
the principal amount of, premium, if any, and accrued interest on the Notes then
outstanding shall automatically become and be immediately due and payable
without any declaration or other act on the part of the Trustee or any Holder.

             The Holders of at least a majority in principal amount of the
outstanding Notes, by written notice to the Company and to the Trustee, may
waive all past defaults and rescind and annul a declaration of acceleration and
its consequences if (i) all existing Events of Default, other than the
nonpayment of the principal of, premium, if any, and interest on the Notes that
have become due solely by such declaration of acceleration, have been cured or
waived and (ii) the rescission would not conflict with any judgment or decree of
a court of competent jurisdiction.

             SECTION 6.03. Other Remedies. If an Event of Default occurs and is
continuing, the Trustee may pursue any available remedy by proceeding at law or
in equity to collect the payment of principal of, premium, if any, or interest
on the Notes or to enforce the performance of any provision of the Notes or this
Indenture.

             The Trustee may maintain a proceeding even if it does not possess
any of the Notes or does not produce any of them in the proceeding.

             SECTION 6.04. Waiver of Past Defaults. Subject to Section 9.02, at
any time after such a declaration of acceleration, but before a judgment or
decree for the payment of the

<PAGE>   68
                                       62

money due has been obtained by the Trustee, the Holders of at least a majority
in aggregate principal amount of the outstanding Notes by written notice to the
Company and to the Trustee may waive all past Defaults and rescind and annul a
declaration of acceleration and its consequences (except a Default in the
payment of principal of premium, if any, or interest on any Note as specified in
clause (a) or (b) of Section 6.01 (but not as a result of such acceleration) or
in respect of a covenant or provision of this Indenture which cannot be modified
or amended without the consent of the Holder of each outstanding Note affected)
if (i) all existing Events of Default, other than the nonpayment of the
principal amount of, premium, if any, and interest on the Notes that have become
due solely by such declaration of acceleration, have been cured or waived and
(ii) the rescission would not conflict with any judgment or decree of a court of
competent jurisdiction. Upon any such waiver, such Default shall cease to exist,
and any Event of Default arising therefrom shall be deemed to have been cured,
for every purpose of this Indenture; but no such waiver shall extend to any
subsequent or other Default or Event of Default or impair any right consequent
thereto.

             SECTION 6.05. Control by Majority. The Holders of at least a
majority in aggregate principal amount of the outstanding Notes may direct the
time, method and place of conducting any proceeding for any remedy available to
the Trustee or exercising any trust or power conferred on the Trustee. However,
the Trustee may refuse to follow any direction that conflicts with law or this
Indenture, that may involve the Trustee in personal liability, or that the
Trustee determines in good faith may be unduly prejudicial to the rights of
Holders of the Notes not joining in the giving of such direction and may take
any other action it deems proper that is not inconsistent with any such
direction received from Holders of the Notes.

             SECTION 6.06. Limitation on Suits. A Holder may not pursue any
remedy with respect to this Indenture or the Notes unless:

             (i) the Holder gives the Trustee written notice of a continuing
        Event of Default;

             (ii) the Holders of at least 25% in aggregate principal amount of
        outstanding Notes make a written request to the Trustee to pursue the
        remedy;

             (iii) such Holder or Holders offer the Trustee indemnity
        satisfactory to the Trustee against any costs, liability or expense;

             (iv) the Trustee does not comply with the request within 60 days
        after receipt of the request and the offer of indemnity; and

             (v) during such 60-day period, the Holders of a majority in
        aggregate principal amount of the outstanding Notes do not give the
        Trustee a direction that is inconsistent with the request.

<PAGE>   69
                                       63

             For purposes of Section 6.05 of this Indenture and this Section
6.06, the Trustee shall comply with TIA Section 316(a) in making any
determination of whether the Holders of the required aggregate principal amount
of outstanding Notes have concurred in any request or direction of the Trustee
to pursue any remedy available to the Trustee or the Holders with respect to
this Indenture or the Notes or otherwise under the law.

             A Holder may not use this Indenture to prejudice the rights of
another Holder or to obtain a preference or priority over such other Holder.

             SECTION 6.07. Rights of Holders to Receive Payment. Notwithstanding
any other provision of this Indenture, the right of any Holder of a Note to
receive payment of principal of, premium, if any, or interest on such Holder's
Note on or after the respective due dates expressed on such Note, or to bring
suit for the enforcement of any such payment on or after such respective dates,
shall not be impaired or affected without the consent of such Holder.

             SECTION 6.08. Collection Suit by Trustee. If an Event of Default in
payment of principal, premium or interest specified in clause (a) or (b) of
Section 6.01 of this Indenture occurs and is continuing, the Trustee may recover
judgment in its own name and as trustee of an express trust against the Company
or any other obligor of the Notes for the whole amount of principal, premium, if
any, and accrued interest remaining unpaid, together with interest on overdue
principal, premium, if any, and, to the extent that payment of such interest is
lawful, interest on overdue installments of interest, in each case at the rate
specified in the Notes, and such further amount as shall be sufficient to cover
the costs and expenses of collection, including the reasonable compensation,
expenses, disbursements and advances of the Trustee, its agents and counsel, and
any other amounts due the Trustee under Section 7.07 hereof.

             SECTION 6.09. Trustee May File Proofs of Claim. The Trustee may
file such proofs of claim and other papers or documents as may be necessary or
advisable in order to have the claims of the Trustee (including any claim for
the reasonable compensation, expenses, disbursements and advances of the
Trustee, its agents and counsel, and any other amounts due the Trustee under
Section 7.07) and the Holders allowed in any judicial proceedings relative to
the Company (or any other obligor of the Notes), its creditors or its property
and the Trustee shall be entitled and empowered to collect and receive any
monies, securities or other property payable or deliverable upon conversion or
exchange of the Notes or upon any such claims and to distribute the same, and
any custodian, receiver, assignee, trustee, liquidator, sequestrator or other
similar official in any such judicial proceeding is hereby authorized by each
Holder to make such payments to the Trustee and, in the event that the Trustee
shall consent to the making of such payments directly to the Holders, to pay to
the Trustee any amount due to it for the reasonable compensation, expenses,
disbursements and advances of the Trustee, its agent and counsel, and any other
amounts due the Trustee under Section 7.07. Nothing herein contained shall be
deemed to empower the Trustee to authorize or consent to, or accept or adopt on
behalf

<PAGE>   70
                                       64

of any Holder, any plan of reorganization, arrangement, adjustment or
composition affecting the Notes or the rights of any Holder thereof, or to
authorize the Trustee to vote in respect of the claim of any Holder in any such
proceeding.

             SECTION 6.10. Priorities. If the Trustee collects any money
pursuant to this Article Six, it shall pay out the money in the following order:

             First: to the Trustee for all amounts due under Section 7.07;

             Second: to Holders for amounts then due and unpaid for principal
        of, premium, if any, and interest on the Notes in respect of which or
        for the benefit of which such money has been collected, ratably, without
        preference or priority of any kind, according to the amounts due and
        payable on such Notes for principal, premium, if any, and interest,
        respectively; and

             Third: to the Company as its interests may appear.

             The Trustee, upon prior written notice to the Company, may fix a
record date and payment date for any payment to Holders pursuant to this Section
6.10.

             SECTION 6.11. Undertaking for Costs. In any suit for the
enforcement of any right or remedy under this Indenture or in any suit against
the Trustee for any action taken or omitted by it as Trustee, a court may
require any party litigant in such suit to file an undertaking to pay the costs
of the suit, and the court may assess reasonable costs, including reasonable
attorneys' fees and expenses, against any party litigant in the suit having due
regard to the merits and good faith of the claims or defenses made by the party
litigant. This Section 6.11 does not apply to a suit by the Trustee, a suit by a
Holder pursuant to Section 6.07 of this Indenture, or a suit by Holders of more
than 10% in principal amount of the outstanding Notes.

             SECTION 6.12. Restoration of Rights and Remedies. If the Trustee or
any Holder has instituted any proceeding to enforce any right or remedy under
this Indenture and such proceeding has been discontinued or abandoned for any
reason, or has been determined adversely to the Trustee or to such Holder, then,
and in every such case, subject to any determination in such proceeding, the
Company, the Trustee and the Holders shall be restored severally and
respectively to their former positions hereunder and thereafter all rights and
remedies of the Company, the Trustee and the Holders shall continue as though no
such proceeding had been instituted.

             SECTION 6.13. Rights and Remedies Cumulative. Except as otherwise
provided with respect to the replacement or payment of mutilated, destroyed,
lost or wrongfully taken Notes in Section 2.09, no right or remedy herein
conferred upon or reserved to the Trustee or to the Holders is intended to be
exclusive of any other right or remedy, and every right and remedy

<PAGE>   71
                                       65

shall, to the extent permitted by law, be cumulative and in addition to every
other right and remedy given hereunder or now or hereafter existing at law or in
equity or otherwise. The assertion or employment of any right or remedy
hereunder, or otherwise, shall not prevent the concurrent assertion or
employment of any other appropriate right or remedy.

             SECTION 6.14. Delay or Omission Not Waiver. No delay or omission of
the Trustee or of any Holder to exercise any right or remedy accruing upon any
Event of Default shall impair any such right or remedy or constitute a waiver of
any such Event of Default or an acquiescence therein. Every right and remedy
given by this Article Six or by law to the Trustee or to the Holders may be
exercised from time to time, and as often as may be deemed expedient, by the
Trustee or by the Holders, as the case may be.

                                  ARTICLE SEVEN
                                     TRUSTEE

             SECTION 7.01. General. The duties and responsibilities of the
Trustee shall be as provided by the TIA and as set forth herein. Notwithstanding
the foregoing, no provision of this Indenture shall require the Trustee to
expend or risk its own funds or otherwise incur any financial liability in the
performance of any of its duties hereunder, or in the exercise of any of its
rights or powers, if it shall have reasonable grounds for believing that
repayment of such funds or adequate indemnity against such risk or liability is
not reasonably assured to it. Whether or not therein expressly so provided,
every provision of this Indenture relating to the conduct or affecting the
liability of or affording protection to the Trustee shall be subject to the
provisions of this Article Seven.

             SECTION 7.02. Certain Rights of Trustee. Subject to TIA Sections
315(a) through (d):

             (i) the Trustee may conclusively rely and shall be protected in
        acting or refraining from acting upon any resolution, certificate,
        statement, instrument, opinion, report, notice, request, direction,
        consent, order, bond, debenture, note, other evidence of indebtedness or
        other paper or document (whether in its original or facsimile form)
        believed by it to be genuine and to have been signed or presented by the
        proper person. The Trustee need not investigate any fact or matter
        stated in the document and may in good faith conclusively rely as to the
        truth of the statements and the correctness of the opinions therein;

             (ii) before the Trustee acts or refrains from acting, it may
        require an Officers' Certificate or an Opinion of Counsel, which shall
        conform to Section 10.04 of this Indenture. The Trustee shall not be
        liable for any action it takes or omits to take in good faith in
        reliance on such certificate or opinion;

<PAGE>   72
                                       66

             (iii) the Trustee may act through its attorneys and agents and
        shall not be responsible for the misconduct or negligence of any agent
        appointed with due care;

             (iv) the Trustee shall be under no obligation to exercise any of
        the rights or powers vested in it by this Indenture at the request or
        direction of any of the Holders, unless such Holders shall have offered
        to the Trustee security or indemnity reasonably satisfactory to it
        against the costs, expenses and liabilities that might be incurred by it
        in complying with such request or direction;

             (v) the Trustee shall not be liable for any action it takes or
        omits to take in good faith that it believes to be authorized or within
        its rights or powers or for any action it takes or omits to take in
        accordance with the direction of the Holders of a majority in principal
        amount of the outstanding Notes relating to the time, method and place
        of conducting any proceeding for any remedy available to the Trustee, or
        exercising any trust or power conferred upon the Trustee, under this
        Indenture; provided that the Trustee's conduct does not constitute
        negligence or bad faith;

             (vi) whenever in the administration of this Indenture the Trustee
        shall deem it desirable that a matter be proved or established prior to
        taking, suffering or omitting to take any action hereunder, the Trustee
        (unless other evidence be herein specifically prescribed) may, in the
        absence of bad faith on its part, rely upon an Officers' Certificate;

             (vii) the Trustee shall not be bound to make any investigation into
        the facts or matters stated in any resolution, certificate, statement,
        instrument, opinion, report, notice, request, direction, consent, order,
        bond, debenture, note, other evidence of indebtedness or other paper or
        document, but the Trustee, in its discretion, may make such further
        inquiry or investigation into such facts or matters as it may see fit,
        and, if the Trustee shall determine to make such further inquiry or
        investigation, it shall be entitled at the sole cost of the Company to
        examine the books, records and premises of the Company personally or by
        agent or attorney and shall incur no liability or additional liability
        of any kind by reason of such inquiry or investigation;

             (viii) the Trustee shall not be charged with knowledge of any
        Default or Event of Default, the identity of any Restricted Subsidiary
        or of the existence of any Change of Control or Asset Sale unless either
        (i) a Responsible Officer shall have actual knowledge thereof, or (ii)
        the Trustee shall have received written notice thereof from the Company
        or any Holder of the Notes; and

             (ix) the Trustee may consult with counsel of its selection and the
        advice of such counsel or any Opinion of Counsel shall be full and
        complete authorization and

<PAGE>   73
                                       67

        protection in respect of any action taken, suffered or omitted to be
        taken by it hereunder in good faith and in reliance thereon.

             SECTION 7.03. Individual Rights of Trustee. The Trustee, in its
individual or any other capacity, may become the owner or pledgee of Notes and
may otherwise deal with the Company or its Affiliates with the same rights it
would have if it were not the Trustee. Any Agent may do the same with like
rights. However, the Trustee is subject to TIA Sections 310(b) and 311.

             SECTION 7.04. Trustee's Disclaimer. The Trustee (a) makes no
representation as to the validity or adequacy of this Indenture or the Notes,
(b) shall not be accountable for the Company's use or application of the
proceeds of the Notes and (c) shall not be responsible for any statement in the
Notes other than its certificate of authentication.

             SECTION 7.05. Notice of Default. If any Default or any Event of
Default occurs and is continuing and if such Default or Event of Default is
known to a Responsible Officer of the Trustee, the Trustee shall mail to each
Holder in the manner and to the extent provided in TIA Section 313(c) notice of
the Default or Event of Default within 90 days after it occurs, unless such
Default or Event of Default has been cured; provided, however, that, except in
the case of a default in the payment of the principal of, premium, if any, or
interest on any Note, the Trustee shall be protected in withholding such notice
if and as long as the board of directors, the executive committee or a trust
committee of directors and/or Responsible Officers of the Trustee in good faith
determine that the withholding of such notice is in the interest of the Holders.
If an Event of Default has occurred and is continuing, the Trustee shall use the
same degree of care and skill in its exercise of the rights and powers invested
in it under this Indenture as a prudent person would exercise under the
circumstances in the conduct of such person's own affairs.

             SECTION 7.06. Reports by Trustee to Holders. Within 60 days after
each May 15, beginning with May 15, 2000, the Trustee shall mail to each Holder
as provided in TIA Section 313(c) a brief report that complies with TIA Section
313(a) dated as of such May 15, if required by TIA Section 313(a).

             SECTION 7.07. Compensation and Indemnity. The Company shall pay to
the Trustee such compensation as shall be agreed upon from time to time in
writing for its services. The compensation of the Trustee shall not be limited
by any law on compensation of a trustee of an express trust. The Company shall
reimburse the Trustee upon request for all reasonable out-of-pocket expenses and
advances incurred or made by the Trustee. Such expenses shall include the
reasonable compensation and expenses of the Trustee's agents and counsel.

             The Company shall indemnify the Trustee and any predecessor trustee
for, and hold it harmless against, any and all loss, claim, damage or liability
or expense (including taxes other than taxes based upon the income of the
Trustee) incurred by it without negligence or bad

<PAGE>   74
                                       68

faith on its part in connection with the acceptance or administration of this
Indenture and its duties under this Indenture and the Notes, including the costs
and expenses of defending itself against any claim or liability and of complying
with any process served upon it or any of its officers in connection with the
exercise or performance of any of its powers or duties under this Indenture and
the Notes. The Trustee shall notify the Company promptly of any claim asserted
against the Trustee for which it may seek indemnity. The Company shall defend
the claim and the Trustee shall provide reasonable cooperation at the Company's
expense in the defense. The Trustee may have separate counsel of its selection
and the Company shall pay the reasonable fees and expenses of such counsel;
provided, that the Company will not be required to pay such fees and expenses if
it assumes the Trustee's defense and counsel selected by Company shall be
diligently and competently representing the Trustee's interests and in the
opinion of the Trustee there is no conflict of interest between the Company and
the Trustee in connection with such defense. The Company need not pay for any
settlement made without its written consent.

             To secure the Company's payment obligations in this Section 7.07,
the Trustee shall have a lien prior to the Noteholders on all money or property
held or collected by the Trustee, in its capacity as Trustee, except money or
property held in trust to pay principal of, premium, if any, and interest on
particular Notes.

             If the Trustee incurs expenses or renders services after the
occurrence of an Event of Default specified in clause (h) or (i) of Section
6.01, the expenses and the compensation for the services will be intended to
constitute expenses of administration under Title 11 of the United States
Bankruptcy Code or any applicable federal or state law for the relief of
debtors.

             The rights, privileges, protections and benefits given to the
Trustee, including, without limitation, its rights to be indemnified, are
extended to, and shall be enforceable by, the Trustee in each of its capacities
hereunder.

             The provisions of this Section 7.07 shall survive the resignation
or removal of the Trustee and the defeasance or other termination of this
Indenture.

             SECTION 7.08. Replacement of Trustee. A resignation or removal of
the Trustee and appointment of a successor Trustee shall become effective only
upon the successor Trustee's acceptance of its appointment as provided in this
Section 7.08.

             The Trustee may resign at any time by so notifying the Company in
writing at least 30 days prior to the date of the proposed resignation. The
Holders of a majority in principal amount of the outstanding Notes may remove
the Trustee by so notifying the Trustee in writing and may appoint a successor
Trustee with the consent of the Company. The Company may at any time remove the
Trustee, by Company Order given at least 30 days prior to the date of the
proposed removal; provided that, at such date, no Event of Default shall have
occurred and be continuing.

<PAGE>   75
                                       69

             If the Trustee resigns or is removed, or if a vacancy exists in the
office of Trustee for any reason, the Company shall promptly appoint a successor
Trustee. Within one year after the successor Trustee takes office, the Holders
of a majority in principal amount of the outstanding Notes may appoint a
successor Trustee to replace the successor Trustee appointed by the Company. If
the successor Trustee does not deliver its written acceptance required by the
next succeeding paragraph of this Section 7.08 within 30 days after the retiring
Trustee resigns or is removed, the retiring Trustee, the Company or the Holders
of a majority in principal amount of the outstanding Notes may petition at the
expense of the Company any court of competent jurisdiction for the appointment
of a successor Trustee.

             A successor Trustee shall deliver a written acceptance of its
appointment to the retiring Trustee and to the Company. Immediately after the
delivery of such written acceptance, subject to the lien provided in Section
7.07 of this Indenture, (i) the retiring Trustee shall transfer all property
held by it as Trustee to the successor Trustee, (ii) the resignation or removal
of the retiring Trustee shall become effective and (iii) the successor Trustee
shall have all the rights, powers and duties of the Trustee under this
Indenture. A successor Trustee shall mail notice of its succession to each
Holder.

             If the Trustee is no longer eligible under Section 7.10 of this
Indenture, any Holder who satisfies the requirements of TIA Section 310(b) may
petition any court of competent jurisdiction for the removal of the Trustee and
the appointment of a successor Trustee.

             The Company shall give notice of any resignation and any removal of
the Trustee and each appointment of a successor Trustee to all Holders. Each
notice shall include the name of the successor Trustee and the address of its
Corporate Trust Office.

             SECTION 7.09. Successor Trustee by Merger, Etc. If the Trustee
consolidates with, merges or converts into, or transfers all or substantially
all of its corporate trust business to, another corporation or national banking
association, the resulting, surviving or transferee corporation or national
banking association without any further act shall be the successor Trustee with
the same effect as if the successor Trustee had been named as the Trustee
herein.

             SECTION 7.10. Eligibility. This Indenture shall always have a
Trustee who satisfies the requirements of TIA Sections 310(a)(1) and 310(a)(5).
The Trustee shall have, or if such Trustee is a member of a bank holding company
system, its bank holding company shall have, a combined capital and surplus of
at least $50,000,000 as set forth in its most recent published annual report of
condition.

             SECTION 7.11. Money Held in Trust. The Trustee shall not be liable
for interest on any money received by it except as the Trustee may agree with
the Company in writing. Money held in trust by the Trustee need not be
segregated from other funds except to the extent required by law and except for
money held in trust under Article Eight of this Indenture.

<PAGE>   76
                                       70

             SECTION 7.12. Withholding Taxes. The Trustee, as agent for the
Company, shall exclude and withhold from each payment of principal and interest
and other amounts due hereunder or under the Notes any and all withholding taxes
applicable thereto as required by law. The Trustee agrees to act as such
withholding agent and, in connection therewith, whenever any present or future
taxes or similar charges are required to be withheld with respect to any amounts
payable in respect of the Notes, to withhold such amounts and timely pay the
same to the appropriate authority in the name of and on behalf of the Holders of
the Notes, that it will file any necessary withholding tax returns or statements
when due, and that, as promptly as possible after the payment thereof, it will
deliver to each Holder of a Note appropriate documentation evidencing the
payment thereof, together with such additional documentary evidence as such
Holders may reasonably request from time to time.

                                  ARTICLE EIGHT
                             DISCHARGE OF INDENTURE

             SECTION 8.01. Termination of the Company's Obligations. Except as
otherwise provided in this Section 8.01, the Company may terminate its
obligations under the Notes and this Indenture if:

             (i) all Notes previously authenticated and delivered (other than
        destroyed, lost or stolen Notes that have been replaced or Notes that
        are paid pursuant to Section 4.01 hereof or Notes for whose payment
        money or securities have theretofore been held in trust and thereafter
        repaid to the Company, as provided in Section 8.05 hereof) have been
        delivered to the Trustee for cancellation and the Company has paid all
        sums payable by it hereunder; or

             (ii) (A) all of the Notes mature within one year or all of them are
        to be called for redemption within one year under arrangements
        satisfactory to the Trustee for giving the notice of redemption, (B) the
        Company deposits in trust with the Trustee during such one-year period,
        under the terms of an irrevocable trust agreement in form and substance
        satisfactory to the Trustee, as trust funds solely for the benefit of
        the Holders for that purpose, money or U.S. Government Obligations
        sufficient to pay principal, premium, if, any, and interest on the Notes
        to maturity or redemption, as the case may be, and to pay all other sums
        payable by it hereunder, (C) no Default or Event of Default with respect
        to the Notes shall have occurred and be continuing on the date of such
        deposit, (D) such deposit will not result in a breach or violation of,
        or constitute a default under, this Indenture or any other agreement or
        instrument to which the Company is a party or by which it is bound, (E)
        if at such time the Notes are listed on a national securities exchange,
        the Notes will not be delisted as a result of such deposit, defeasance
        or discharge and (F) the Company has delivered to the Trustee an
        Officers' Certificate and

<PAGE>   77
                                       71

        an Opinion of Counsel, in each case stating that all conditions
        precedent provided for herein relating to the satisfaction and discharge
        of this Indenture have been complied with.

             With respect to the foregoing clause (i), the Company's obligations
under Section 7.07 hereof shall survive. With respect to the foregoing clause
(ii), the Company's obligations in Sections 2.02, 2.03, 2.04, 2.05, 2.06, 2.07,
2.08, 2.09, 2.14, 4.01, 4.02, 7.07, 7.08, 8.04, 8.05 and 8.06 of this Indenture
shall survive until the Notes are no longer outstanding. Thereafter, only the
Company's obligations in Sections 7.07, 8.05 and 8.06 of this Indenture shall
survive. After any such irrevocable deposit, the Trustee upon request shall
acknowledge in writing the discharge of the Company's obligations, as the case
may be, under the Notes and this Indenture, except for those surviving
obligations specified above.

             SECTION 8.02. Defeasance and Discharge of Indenture. The Company
will be deemed to have paid and will be discharged from any and all obligations
in respect of the Notes on the 123rd day after the deposit referred to below,
and the provisions of this Indenture will no longer be in effect with respect to
the Notes (except for, among other matters, certain obligations to register the
transfer or exchange of the Notes, to replace stolen, lost or mutilated Notes,
to maintain paying agencies and to hold monies for payment in trust) if, among
other things:

             (A) the Company has deposited with the Trustee, in trust, money
        and/or U.S. Government Obligations that through the payment of interest
        and principal in respect thereof in accordance with their terms will
        provide money in an amount sufficient in the opinion of a nationally
        recognized independent public accounting firm to pay the principal of,
        premium, if any, and accrued interest on the Notes on the Stated
        Maturity of such payments in accordance with the terms of this Indenture
        and the Notes;

             (B) the Company has delivered to the Trustee (i) either (x) an
        Opinion of Counsel to the effect that Holders will not recognize income,
        gain or loss for federal income tax purposes as a result of the
        Company's exercise of its option under this Section 8.02 and will be
        subject to federal income tax on the same amount and in the same manner
        and at the same times as would have been the case if such deposit,
        defeasance and discharge had not occurred, which Opinion of Counsel must
        be based upon (and accompanied by a copy of) a ruling of the Internal
        Revenue Service to the same effect unless there has been a change in
        applicable federal income tax law after the Closing Date such that a
        ruling is no longer required or (y) a ruling directed to the Trustee
        received from the Internal Revenue Service to the same effect as the
        aforementioned Opinion of Counsel and (ii) an Opinion of Counsel to the
        effect that the creation of the defeasance trust does not violate the
        Investment Company Act of 1940 and after the passage of 123 days
        following the deposit, the trust fund will not be subject to the effect
        of Section 547 of the United States Bankruptcy Code or Section 15 of the
        New York Debtor and Creditor Law;

<PAGE>   78
                                       72

             (C) immediately after giving effect to such deposit on a pro forma
        basis, no Event of Default, or event that after the giving of notice or
        lapse of time or both would become an Event of Default, shall have
        occurred and be continuing on the date of such deposit or during the
        period ending on the 123rd day after the date of such deposit, and such
        deposit shall not result in a breach or violation of, or constitute a
        default under, any other agreement or instrument to which the Company or
        any of its Subsidiaries is a party or by which the Company or any of its
        Subsidiaries is bound; and

             (D) if at such time the Notes are listed on a national securities
        exchange, the Company has delivered to the Trustee an Opinion of Counsel
        to the effect that the Notes will not be delisted as a result of such
        deposit, defeasance and discharge.

             Notwithstanding the foregoing, prior to the end of the 123-day
period referred to in clause (B)(ii) of this Section 8.02, none of the Company's
obligations under this Indenture shall be discharged. Subsequent to the end of
such 123-day period with respect to this Section 8.02, the Company's obligations
in Sections 2.02, 2.03, 2.04, 2.05, 2.06, 2.07, 2.08, 2.09, 2.14, 4.01, 4.02,
4.17, 7.07, 7.08, 8.05 and 8.06 shall survive until the Notes are no longer
outstanding. Thereafter, only the Company's obligations in Sections 7.07, 8.05
and 8.06 shall survive. If and when a ruling from the Internal Revenue Service
or an Opinion of Counsel referred to in clause (B)(i) of this Section 8.02 may
be provided specifically without regard to, and not in reliance upon, the
continuance of the Company's obligations under Section 4.01, then the Company's
obligations under such Section 4.01 shall cease upon delivery to the Trustee of
such ruling or Opinion of Counsel and compliance with the other conditions
precedent provided for herein relating to the defeasance contemplated by this
Section 8.02.

             After the 123 day period referred to in clause (B)(ii) of this
Section 8.02, the Trustee upon Company Order shall acknowledge in writing the
discharge of the Company's obligations under the Notes and this Indenture except
for those surviving obligations in the immediately preceding paragraph.

             SECTION 8.03. Defeasance of Certain Obligations. The Company may
omit to comply with any term, provision or condition set forth in clause (iii)
of Section 5.01, Sections 4.03 through 4.13 and Section 4.19 of this Indenture,
and clause (c) of Section 6.01 with respect to clause (iii) of Section 5.01 of
this Indenture, clause (d) of Section 6.01 with respect to Sections 4.01, 4.02,
4.14 through 4.18 and Section 4.20 hereof, and clauses (e) and (f) of Section
6.01 hereof shall be deemed not to be Events of Default, upon:

             (a) the deposit, in trust, with the Trustee (or another trustee
        satisfying the requirements of Section 7.10 hereof) of money and/or U.S.
        Government Obligations that, through the payment of interest and
        principal in respect thereof in accordance with their terms, will
        provide money in an amount sufficient in the opinion of a nationally

<PAGE>   79
                                       73

        recognized independent public accounting firm to pay the principal of,
        premium, if any, and accrued interest on the Notes on the Stated
        Maturity of such payments in accordance with the terms of this Indenture
        and the Notes;

             (b) the satisfaction of the provisions described in clauses B(ii),
        (C) and (D) of Section 8.02 hereof;

             (c) delivery by the Company to the Trustee of an Opinion of Counsel
        to the effect that, the Holders will not recognize income, gain or loss
        for federal income tax purposes as a result of such deposit and
        defeasance and will be subject to federal income tax on the same amount
        and in the same manner and at the same times as would have been the case
        if such deposit and defeasance had not occurred; and

             (d) the Company shall have delivered to the Trustee an Officers'
        Certificate and an Opinion of Counsel, in each case stating that all
        conditions precedent provided for herein relating to the defeasance
        contemplated by this Section 8.03 have been complied with.

             SECTION 8.04. Application of Trust Money. Subject to Section 8.06,
the Trustee or Paying Agent shall hold in trust money or U.S. Government
Obligations deposited with it pursuant to Section 8.01, 8.02 or 8.03, as the
case may be, and shall apply the deposited money and the money from U.S.
Government Obligations in accordance with the Notes and this Indenture to the
payment of principal of, premium, if any, and interest on the Notes; but such
money need not be segregated from other funds except to the extent required by
law.

             SECTION 8.05. Repayment to Company. Subject to Sections 7.07, 8.01,
8.02 and 8.03, the Trustee and the Paying Agent shall promptly pay to the
Company any excess money, as determined by a nationally recognized firm of
independent public accountants expressed in a written certification thereof
delivered to the Trustee, and held by them at any time and thereupon shall be
relieved from all liability with respect to such money. The Trustee and the
Paying Agent shall pay to the Company upon request, subject to applicable state
escheatment laws, any money held by them for the payment of principal, premium,
if any, or interest that remains unclaimed for two years; provided that the
Trustee or such Paying Agent before being required to make any payment may cause
to be published at the expense of the Company once in a newspaper of general
circulation in the City of New York or mail to each Holder entitled to such
money at such Holder's address (as set forth in the Note Register) notice that
such money remains unclaimed provided that the Trustee or such Paying Agent
before being required to make any payment may give notice in accordance with
Section 11.02(b) that such money remains unclaimed and that after a date
specified therein (which shall be at least 30 days from the date of such
publication or mailing) any unclaimed balance of such money then remaining will
be repaid to the Company. After payment to the Company, Holders entitled to such
money must look to the Company for payment as general creditors unless an
applicable law designates another

<PAGE>   80
                                       74

Person, and all liability of the Trustee and such Paying Agent with respect to
such money shall cease.

             SECTION 8.06. Reinstatement. If the Trustee or the Paying Agent is
unable to apply any money or U.S. Government Obligations in accordance with
Section 8.01, 8.02 or 8.03, as the case may be, by reason of any legal
proceeding or by reason of any order or judgment of any court or governmental
authority enjoining, restraining or otherwise prohibiting such application, the
Company's obligations under this Indenture and the Notes shall be revived and
reinstated as though no deposit had occurred pursuant to Section 8.01, 8.02 or
8.03, as the case may be, until such time as the Trustee or Paying Agent is
permitted to apply all such money or U.S. Government Obligations in accordance
with Section 8.01, 8.02 or 8.03, as the case may be; provided that, if the
Company has made any payment of principal of, premium, if any, or interest on
any Notes because of the reinstatement of its obligations, the Company shall be
subrogated to the rights of the Holders of such Notes to receive such payment
from the money or U.S. Government Obligations held by the Trustee or Paying
Agent.

             SECTION 8.07. Defeasance and Certain Other Events of Default. In
the event that the Company exercises its option to omit compliance with certain
covenants and provisions of this Indenture with respect to the Notes pursuant to
Section 8.03 and such Notes are declared due and payable because of the
occurrence of an Event of Default that remains applicable, the amount of money
and/or U.S. Government Obligations on deposit with the Trustee will be
sufficient to pay amounts due on such Notes at the time of their Stated
Maturity. If, in the event the Company exercises its option to omit compliance
with certain covenants and provisions of this Indenture with respect to the
Notes pursuant to Section 8.03 and such Notes are declared due and payable
because of the occurrence of an Event of Default that remains applicable, the
amount of money and/or U.S. Government Obligations on deposit with the Trustee
is insufficient to pay amounts due on the Notes at the time of the acceleration
resulting from such Events of Default pursuant to Section 6.02, the Company will
remain liable for such payments.

                                  ARTICLE NINE
                       AMENDMENTS, SUPPLEMENTS AND WAIVERS

             SECTION 9.01. Without Consent of Holders. The Company, when
authorized by resolutions of its Board of Directors (as evidenced by a Board
Resolution), and the Trustee may amend or supplement this Indenture or the Notes
without notice to, or the consent of, any Holder:

             (a) to cure any ambiguity, defect or inconsistency in this
        Indenture;

             (b) to comply with Section 4.07 or Article Five;

<PAGE>   81
                                       75

             (c) to comply with any requirements of the Commission in connection
        with the qualification of this Indenture under the TIA;

             (d) to evidence and provide for the acceptance of appointment by a
        successor Trustee; or

             (e) to make any change that, in the good faith opinion of the Board
        of Directors, does not materially and adversely affect the rights of any
        Holder (including, without limitation, allowing resales of the Notes
        under and in accordance with Regulation S of the U.S. securities laws).

             SECTION 9.02. With Consent of Holders. Subject to Sections 6.07 and
without prior notice to the Holders, the Company, when authorized by its Board
of Directors (as evidenced by a Board Resolution), and the Trustee may amend
this Indenture and the Notes with the written consent of the Holders of a
majority in aggregate principal amount of the Notes then outstanding, and the
Holders of a majority in aggregate principal amount of the Notes then
outstanding by written notice to the Trustee may waive compliance by the Company
with any provision of this Indenture or the Notes.

             Notwithstanding the provisions of this Section 9.02, without the
consent of each Holder affected thereby, an amendment or waiver, including a
waiver pursuant to Section 6.04 hereof, may not:

             (a) change the Stated Maturity of the principal of, or any
        installment of interest on, any Note;

             (b) reduce the principal amount of, or premium, if any, or interest
        on, any Note;

             (c) change the optional redemption dates or optional redemption
        prices of the Notes from that stated in Section 3.01;

             (d) change the place or currency of payment of principal of, or
        premium if any, or interest on, any Note;

             (e) impair the right to institute suit for the enforcement of any
        payment on or after the Stated Maturity (or, in the case of a
        redemption, on or after the Redemption Date) of any Note;

             (f) waive a default in the payment of principal of, premium, if
        any, or interest on the Notes;

<PAGE>   82
                                       76

             (g) release any Subsidiary Guarantor from its Note Guarantee,
        except as provided in this Indenture; or

             (h) reduce the percentage or aggregate principal amount of
        outstanding Notes the consent of whose Holders is necessary for waiver
        of compliance with certain provisions of this Indenture or for waiver of
        certain defaults.

             It shall not be necessary for the consent of the Holders under this
Section 9.02 to approve the particular form of any proposed amendment,
supplement or waiver, but it shall be sufficient if such consent approves the
substance thereof.

             After an amendment, supplement or waiver under this Section 9.02
becomes effective, the Trustee shall mail to the Holders affected thereby a
notice briefly describing the amendment, supplement or waiver. The Company will
mail supplemental indentures to Holders upon request. Any failure of the Company
to mail such notice, or any defect therein, shall not, however, in any way
impair or affect the validity of any such supplemental indenture or waiver.

             SECTION 9.03. Revocation and Effect of Consent. Until an amendment
or waiver becomes effective, a consent to it by a Holder is a continuing consent
by the Holder and every subsequent Holder of a Note or portion of a Note that
evidences the same debt as the Note of the consenting Holder, even if notation
of the consent is not made on any Note. However, any such Holder or subsequent
Holder may revoke the consent as to its Note or portion of its Note. Such
revocation shall be effective only if the Trustee receives the notice of
revocation before the date the amendment, supplement or waiver becomes
effective. An amendment, supplement or waiver shall become effective on receipt
by the Trustee of written consents from the Holders of the requisite percentage
in principal amount of the outstanding Notes.

             The Company may, but shall not be obligated to, fix a record date
for the purpose of determining the Holders entitled to consent to any amendment,
supplement or waiver. If a record date is fixed, then, notwithstanding the last
two sentences of the immediately preceding paragraph, those Persons who were
Holders at such record date (or their duly designated proxies) and only those
Persons shall be entitled to consent to such amendment, supplement or waiver or
to revoke any consent previously given, whether or not such Persons continue to
be Holders after such record date. No such consent shall be valid or effective
for more than 90 days after such record date.

             After an amendment, supplement or waiver becomes effective, it
shall bind every Holder unless it is of the type described in any of clauses (i)
through (vii) of Section 9.02. In case of an amendment or waiver of the type
described in clauses (i) through (vii) of Section 9.02, the amendment or waiver
shall bind each Holder who has consented to it and every subsequent Holder of a
Note that evidences the same indebtedness as the Note of the consenting Holder.

<PAGE>   83
                                       77

             SECTION 9.04. Notation on or Exchange of Notes. If an amendment,
supplement or waiver changes the terms of a Note, the Trustee may require the
Holder to deliver it to the Trustee. The Trustee may place an appropriate
notation on the Note about the changed terms and return it to the Holder and the
Trustee may place an appropriate notation on any Note thereafter authenticated.
Alternatively, if the Company or the Trustee so determines, the Company in
exchange for the Note shall issue and the Trustee shall authenticate a new Note
that reflects the changed terms.

             SECTION 9.05. Trustee to Sign Amendments, Etc. The Trustee shall be
entitled to receive, and shall be fully protected in relying upon, in addition
to the documents required by Section 11.03, an Opinion of Counsel stating that
the execution of any amendment, supplement or waiver authorized pursuant to this
Article Nine is authorized or permitted by this Indenture. Subject to the
preceding sentence, the Trustee shall sign such amendment, supplement or waiver
if the same does not adversely affect the rights of the Trustee. The Trustee
may, but shall not be obligated to, execute any such amendment, supplement or
waiver that affects the Trustee's own rights, duties or immunities under this
Indenture or otherwise.

             SECTION 9.06. Conformity with Trust Indenture Act. Every
supplemental indenture executed pursuant to this Article Nine shall conform to
the requirements of the TIA as then in effect.

                                   ARTICLE TEN
                                    SECURITY

        SECTION 10.01. Security. (a) On the Closing Date, the Company shall (i)
enter into the Pledge Agreement and comply with the terms and provisions thereof
and (ii) purchase the Pledged Securities to be pledged to the Trustee for the
benefit of the Holders in such amount as will be sufficient upon receipt of
scheduled interest and/or principal payments of such Pledged Securities to
provide for payment in full of the first four scheduled interest payments due on
the Notes. The Pledged Securities shall be pledged by the Company to the Trustee
for the benefit of the Holders and shall be held by the Trustee in the Pledge
Account pending disposition pursuant to the Pledge Agreement.

        (b) Each Holder, by its acceptance of a Note, consents and agrees to the
terms of the Pledge Agreement (including, without limitation, the provisions
providing for foreclosure and release of the Pledged Securities) as the same may
be in effect or may be amended from time to time in accordance with its terms,
and authorizes and directs the Trustee to enter into the Pledge Agreement and to
perform its respective obligations and exercise its respective rights thereunder
in accordance therewith. The Company will do or cause to be done all such acts
and things as may be necessary or reasonably requested by the Trustee, or as may
be required by the provisions of the Pledge Agreement, to assure and confirm to
the Trustee the security interest in

<PAGE>   84
                                       78

the Pledged Securities contemplated hereby, by the Pledge Agreement or any part
thereof, as from time to time constituted, so as to render the same available
for the security and benefit of this Indenture and of the Notes secured hereby,
according to the intent and purposes herein and therein expressed. The Company
shall take, or shall cause to be taken, upon request of the Trustee, any and all
actions reasonably required to cause the Pledge Agreement to create and
maintain, as security for the obligations of the Company under this Indenture
and the Notes, valid and enforceable first priority liens in and on all the
Pledged Securities, in favor of the Trustee, superior to and prior to the rights
of third Persons and subject to no other Liens.

             (c) The release of any Pledged Securities pursuant to the Pledge
Agreement will not be deemed to impair the security under this Indenture in
contravention of the provisions hereof if and to the extent the Pledged
Securities are released pursuant to this Indenture and the Pledge Agreement. To
the extent applicable, the Company shall cause TIA Section 314(d) relating to
the release of property or securities from the Lien and security interest of the
Pledge Agreement and relating to the substitution therefor of any property or
securities to be subjected to the Lien and security interest of the Pledge
Agreement to be complied with. Any certificate or opinion required by TIA
Section 314(d) may be made by an Officer of the Company, except in cases where
TIA Section 314(d) requires that such certificate or opinion be made by an
independent Person, which Person shall be an independent engineer, appraiser or
other expert selected by the Company.

             (d) The Company shall cause TIA Section 314(b), relating to
opinions of counsel regarding the Lien under the Pledge Agreement, to be
complied with. The Trustee may accept, to the extent permitted by Sections 4.18
and 7.06 as conclusive evidence of compliance with the foregoing provisions, the
appropriate statements contained in such instruments.

             (e) The Trustee may, in its sole discretion and without the consent
of the Holders, on behalf of the Holders, take all reasonable actions in
accordance with the Pledge Agreement necessary or appropriate in order to (i)
enforce any of the terms of the Pledge Agreement and (ii) collect and receive
any and all amounts payable in respect of the obligations of the Company
thereunder. The Trustee shall have power to institute and to maintain such suits
and proceedings as the Trustee may reasonably deem expedient to preserve or
protect its interests and the interests of the Holders in the Pledged Securities
(including power to institute and maintain suits or proceedings to restrain the
enforcement of or compliance with any legislative or other governmental
enactment, rule or order that may be unconstitutional or otherwise invalid if
the enforcement of, or compliance with, such enactment, rule or order would
impair the security interest hereunder or be prejudicial to the interests of the
Holders or of the Trustee).

                                 ARTICLE ELEVEN
                                  MISCELLANEOUS

<PAGE>   85
                                       79

             SECTION 11.01. Trust Indenture Act of 1939. Prior to the
effectiveness of the Registration Statement, this Indenture shall incorporate
and be governed by the provisions of the TIA that are required or deemed to be
part of and to govern indentures qualified under the TIA. After the
effectiveness of the Registration Statement, this Indenture shall be subject to
the provisions of the TIA that are required or deemed to be a part of this
Indenture and shall, to the extent applicable, be governed by such provisions.

             SECTION 11.02. Notices. (a) Any notice or communication shall be
sufficiently given if in writing and delivered in person or mailed by first
class mail, commercial courier service or telecopier communication, addressed as
follows:

               if to the Company:

                      COLO.COM
                      2000 Sierra Point Parkway
                      Brisbane, California  94005
                      Telecopier Number:  (650) 244-7727
                      Attention:  David H. Stanley

                      With, in the case of any notice given pursuant to Article
                      Six, a copy to:

                      Wilson Sonsini Goodrich & Rosati
                      650 Page Mill Road
                      Palo Alto, California  94304-1050
                      Telecopier Number:  (650) 493-6811
                      Attention:  Michael Dorf

               if to the Trustee:

                      State Street Bank and Trust Company of California, N.A.
                      633 West 5th Street, 12th Floor
                      Los Angeles, CA  90071
                      Telecopier Number:  (213) 362-7357
                      Attention:  Corporate Trust Department,
                                 COLO.COM 137/8% Senior
                                 Notes due 2010

<PAGE>   86
                                       80

                      With a copy to:

                      Robert M. Borden, Esq.
                      Bingham Dana LLP
                      One State Street
                      Hartford, CT  06103
                      Telecopier Number:  (860) 240-2800

             The Company, the Trustee, or the Depository by notice to the others
may designate additional or different addresses for subsequent notices or
communications.

             All notices and communications (other than those sent to Holders)
shall be deemed to have been duly given: at the time delivered by hand, if
personally delivered; five Business Days after being deposited in the mail,
postage prepaid, if mailed; when receipt acknowledged, if telecopied; and the
next Business Day after timely delivery to the courier, if sent by overnight air
courier guaranteeing next day delivery.

             (b) Any notice or communication mailed to a Holder shall be mailed
to him at his address as it appears on the Note Register by first class mail and
shall be sufficiently given to him if so mailed within the time prescribed.
Copies of any such communication or notice to a Holder shall also be mailed to
the Trustee and each Agent at the same time.

             Failure to mail a notice or communication to a Holder or any defect
in it shall not affect its sufficiency with respect to other Holders. Except for
a notice to the Trustee, which is deemed given only when received, and except as
otherwise provided in this Indenture, if a notice or communication is mailed in
the manner provided in this Section 11.02, it is duly given, whether or not the
addressee receives it.

             (c) Where this Indenture provides for notice in any manner, such
notice may be waived in writing by the Person entitled to receive such notice,
either before or after the event, and such waiver shall be the equivalent of
such notice. Waivers of notice by Holders shall be filed with the Trustee, but
such filing shall not be a condition precedent to the validity of any action
taken in reliance upon such waiver.

             In case by reason of the suspension of regular mail service or by
reason of any other cause it shall be impracticable to give such notice by mail,
then such notification as shall be made with the approval of the Trustee shall
constitute a sufficient notification for every purpose hereunder.

             SECTION 11.03. Certificate and Opinion as to Conditions Precedent.
Upon any request or application by the Company to the Trustee to take any action
under this Indenture, the Company shall furnish to the Trustee:

<PAGE>   87
                                       81

             (a) an Officers' Certificate stating that, in the opinion of the
        signers, all conditions precedent, if any, provided for in this
        Indenture relating to the proposed action have been complied with; and

             (b) an Opinion of Counsel stating that, in the opinion of such
        Counsel, all such conditions precedent have been complied with.

             SECTION 11.04. Statements Required in Certificate or Opinion. Each
certificate or opinion with respect to compliance with a condition or covenant
provided for in this Indenture shall include:

             (a) a statement that each person signing such certificate or
        opinion has read such covenant or condition and the definitions herein
        relating thereto;

             (b) a brief statement as to the nature and scope of the examination
        or investigation upon which the statement or opinion contained in such
        certificate or opinion is based;

             (c) a statement that, in the opinion of each such person, he has
        made such examination or investigation as is necessary to enable him to
        express an informed opinion as to whether or not such covenant or
        condition has been complied with; and

             (d) a statement as to whether or not, in the opinion of each such
        person, such condition or covenant has been complied with; provided,
        however, that, with respect to matters of fact, an Opinion of Counsel
        may rely on an Officers' Certificate or certificates of public
        officials.

             SECTION 11.05. Rules by Trustee, Paying Agent or Registrar. The
Trustee may make reasonable rules for action by or at a meeting of Holders. The
Paying Agent or Registrar may make reasonable rules for its functions.

             SECTION 11.06. Payment Date Other Than a Business Day. If an
Interest Payment Date, Redemption Date, Payment Date, Stated Maturity or date of
maturity of any Note shall not be a Business Day, then payment of principal of,
premium, if any, or interest on such Note, as the case may be, need not be made
on such date, but may be made on the next succeeding Business Day with the same
force and effect as if made on the Interest Payment Date, Payment Date, or
Redemption Date, or at the Stated Maturity or date of maturity of such Note;
provided that no interest shall accrue for the period from and after such
Interest Payment Date, Payment Date, Redemption Date, Stated Maturity or date of
maturity, as the case may be.

<PAGE>   88
                                       82

             SECTION 11.07. Governing Law; Submission to Jurisdiction; Agent for
Service. This Indenture and the Notes shall be governed by the laws of the State
of New York. The Trustee, the Company and the Holders agree to submit to the
jurisdiction of the courts of the State of New York in any action or proceeding
arising out of or relating to this Indenture or the Notes.

             SECTION 11.08. No Adverse Interpretation of Other Agreements. This
Indenture may not be used to interpret another indenture, loan or debt agreement
of the Company or any Subsidiary of the Company. Any such indenture, loan or
debt agreement may not be used to interpret this Indenture.

             SECTION 11.09. No Recourse Against Others. No recourse for the
payment of the principal of, premium, if any, or interest on any of the Notes,
or for any claim based thereon or otherwise in respect thereof, and no recourse
under or upon any obligation, covenant or agreement of the Company contained in
this Indenture, or in any of the Notes, or because of the creation of any
Indebtedness represented thereby, shall be had against any incorporator or
against any past, present or future partner, stockholder, other equity holder,
officer, director, employee or controlling person, as such, of the Company or of
any successor Person, either directly or through the Company or any successor
Person, whether by virtue of any constitution, statute or rule of law, or by the
enforcement of any assessment or penalty or otherwise; it being expressly
understood that all such liability is hereby expressly waived and released as a
condition of, and as a consideration for, the execution of this Indenture and
the issue of the Notes.

             SECTION 11.10. Successors. All agreements of the Company in this
Indenture and the Notes shall bind its successors. All agreements of the Trustee
in this Indenture shall bind its successors.

             SECTION 11.11. Duplicate Originals. The parties may sign any number
of copies of this Indenture. Each signed copy shall be an original, but all of
them together represent the same agreement.

             SECTION 11.12. Separability. In case any provision in this
Indenture or in the Notes shall be invalid, illegal or unenforceable, the
validity, legality and enforceability of the remaining provisions shall not in
any way be affected or impaired thereby.

             SECTION 11.13. Table of Contents, Headings, Etc. The Table of
Contents, Cross-Reference Table and headings of the Articles and Sections of
this Indenture have been inserted for convenience of reference only, are not to
be considered a part hereof and shall in no way modify or restrict any of the
terms and provisions hereof.

<PAGE>   89

                                   SIGNATURES

             IN WITNESS WHEREOF, the parties hereto have caused this Indenture
to be duly executed, all as of the date first written above.

                                       COLO.COM

                                       By: /s/ Charles M. Skibo
                                          ------------------------------------
                                       Name: Charles M. Skibo
                                       Title: President and Chief Executive
                                              Officer

                                       STATE STREET BANK AND TRUST COMPANY OF
                                       CALIFORNIA, N.A.
                                       as Trustee

                                       By: /s/ Scott C. Emmons
                                          ------------------------------------
                                       Name:  Scott C. Emmons
                                       Title:    Vice President

<PAGE>   90

                                                                       EXHIBIT A

                               FORM OF GLOBAL NOTE

                                  FACE OF NOTE

THE SECURITIES EVIDENCED HEREBY HAVE NOT BEEN REGISTERED UNDER THE UNITED STATES
SECURITIES ACT OF 1933, AS AMENDED (THE "SECURITIES ACT"), AND MAY NOT BE
OFFERED, SOLD, PLEDGED OR OTHERWISE TRANSFERRED EXCEPT (1) TO A PERSON WHOM THE
SELLER REASONABLY BELIEVES IS A QUALIFIED INSTITUTIONAL BUYER WITHIN THE MEANING
OF RULE 144A UNDER THE SECURITIES ACT PURCHASING FOR ITS OWN ACCOUNT OR FOR THE
ACCOUNT OF A QUALIFIED INSTITUTIONAL BUYER IN A TRANSACTION MEETING THE
REQUIREMENTS OF RULE 144A, (2) PURSUANT TO AN EXEMPTION FROM REGISTRATION UNDER
THE SECURITIES ACT PROVIDED BY RULE 144 THEREUNDER (IF AVAILABLE), (3) TO AN
INSTITUTIONAL ACCREDITED INVESTOR IN A TRANSACTION EXEMPT FROM THE REGISTRATION
REQUIREMENTS UNDER REGULATION D UNDER THE SECURITIES ACT OR (4) PURSUANT TO AN
EFFECTIVE REGISTRATION STATEMENT UNDER THE SECURITIES ACT, IN EACH CASE, IN
ACCORDANCE WITH ALL APPLICABLE SECURITIES LAWS OF THE STATES OF THE UNITED
STATES.

UNLESS THIS GLOBAL NOTE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE
DEPOSITORY TRUST COMPANY TO COLO.COM OR ITS AGENT FOR REGISTRATION OF TRANSFER,
EXCHANGE OR PAYMENT, AND ANY NOTE ISSUED IS REGISTERED IN THE NAME OF CEDE & CO.
OR TO SUCH OTHER ENTITY AS IS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF THE
DEPOSITORY TRUST COMPANY OR SUCH OTHER REPRESENTATIVE OF THE DEPOSITORY TRUST
COMPANY OR SUCH OTHER NAME AS IS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF
THE DEPOSITORY TRUST COMPANY (AND ANY PAYMENT HEREON IS MADE TO CEDE & CO. OR TO
SUCH OTHER ENTITY AS IS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF THE
DEPOSITORY TRUST COMPANY), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR
OTHERWISE BY OR TO ANY PERSON IS WRONGFUL SINCE THE REGISTERED OWNER HEREOF,
CEDE & CO., HAS AN INTEREST HEREIN.

TRANSFERS OF THIS GLOBAL NOTE SHALL BE LIMITED TO TRANSFERS IN WHOLE, BUT NOT IN
PART, TO NOMINEES OF CEDE & CO. OR TO A SUCCESSOR THEREOF OR SUCH SUCCESSOR'S
NOMINEE AND TRANSFERS OF PORTIONS OF THIS GLOBAL NOTE SHALL BE LIMITED TO
TRANSFERS MADE IN ACCORDANCE WITH THE RESTRICTIONS SET FORTH IN SECTION 2.08 OF
THE INDENTURE.

THIS NOTE IS INITIALLY ISSUED AS PART OF AN ISSUANCE OF UNITS, EACH OF WHICH
CONSISTS OF ONE NOTE AND ONE WARRANT INITIALLY ENTITLING THE

<PAGE>   91
                                      A-2

HOLDER THEREOF TO PURCHASE 19.9718 SHARES OF COMMON STOCK, PAR VALUE $0.01 PER
SHARE, OF COLO.COM (A "WARRANT"). PRIOR TO THE CLOSE OF BUSINESS UPON THE
EARLIEST TO OCCUR OF (i) MARCH 10, 2001, (ii) 180 DAYS AFTER THE CLOSING DATE OF
THE COMPANY'S INITIAL PUBLIC OFFERING, (iii) THE COMMENCEMENT OF AN EXCHANGE
OFFER WITH RESPECT TO THE NOTES, (iv) THE EFFECTIVENESS OF A SHELF REGISTRATION
STATEMENT WITH RESPECT TO THE NOTES, (v) THE COMMENCEMENT OF AN OFFER TO
PURCHASE THE NOTES UPON A CHANGE OF CONTROL OR (vi) SUCH DATE AS DETERMINED BY
GOLDMAN, SACHS & CO. IN ITS SOLE DISCRETION, THE NOTES EVIDENCED BY THIS
CERTIFICATE MAY NOT BE TRANSFERRED OR EXCHANGED SEPARATELY FROM, BUT MAY BE
TRANSFERRED OR EXCHANGED ONLY TOGETHER WITH, THE WARRANTS.

<PAGE>   92
                                      A-3

                                    COLO.COM

                          13 7/8% Senior Note Due 2010

                                                        [CUSIP][CINS][ISIN][___]
No.  __________                                                       $[_______]

        Issue date: _______, ____

        COLO.COM, a California corporation (the "Company", which term includes
any successor under the Indenture hereinafter referred to), for value received,
promises to pay to ________________, or its registered assigns, upon surrender
hereof the principal sum of $___________ on March 15, 2010.

        Interest Payment Dates: March 15 and September 15, commencing September
15, 2000.

        Record Dates: March 1 and September 1.

        Reference is hereby made to the further provisions of this Note set
forth on the reverse hereof, which further provisions shall for all purposes
have the same effect as if set forth at this place.

<PAGE>   93

        IN WITNESS WHEREOF, the Company has caused this Note to be signed
manually or by facsimile by its duly authorized officers.

Date:  __________                      COLO.COM

                                       By:
                                          ------------------------------------
                                            Name:
                                            Title:

                    (Trustee's Certificate of Authentication)

This is one of the 13 7/8% Senior Notes due 2010 described in the
within-mentioned Indenture.

Date: ___________                     STATE STREET BANK AND TRUST COMPANY
                                      OF CALIFORNIA, N.A., as Trustee

                                      By:
                                          ------------------------------------
                                             Authorized Signatory

<PAGE>   94
                                      A-5

                             [REVERSE SIDE OF NOTE]

                                    COLO.COM

                          13 7/8% Senior Note due 2010

1. Principal and Interest.

             The Company will pay the principal of this Note on March 15, 2010.

             The Company promises to pay interest on the principal amount of
this Note on each Interest Payment Date, as set forth below, at the rate per
annum shown above.

             Interest will be payable semiannually in cash (to the holders of
record of the Notes at the close of business on the March 15 or September 15
immediately preceding the Interest Payment Date) on each Interest Payment Date,
commencing September 15, 2000. Interest will be computed on the basis of a
360-day year of twelve 30-day months.

             If an exchange offer registered under the Securities Act is not
consummated, and a shelf registration statement under the Securities Act with
respect to resales of the Notes is not declared effective by the Commission, on
or before the date that is six months after the Closing Date in accordance with
the terms of the Registration Rights Agreement, dated March 10, 2000, between
the Company and Goldman, Sachs & Co., as the manager for itself and the several
initial purchasers named on Schedule I to the Purchase Agreement, dated March 3,
2000, annual interest (in addition to interest otherwise due on the Notes) will
accrue, at an annual rate equal to 0.25% for the first 90 days thereafter, 0.50%
for the second 90 days thereafter, 0.75% for the third 90 days thereafter and
1.00% thereafter until the consummation of a registered exchange offer or the
effectiveness of a shelf-registration statement with respect to resale of this
Note. The Holder of this Note is entitled to the benefits of such Registration
Rights Agreement.

             The Holder of this Note is entitled to the benefits of a Pledge
Agreement, dated March 10, 2000, between the Company and State Street Bank and
Trust Company of California, N.A., as trustee (the "Trustee"), pursuant to which
the Company has placed in the Pledge Account cash or Government Securities
sufficient to provide for the payment of the first four interest payments on
this Note.

             The Company shall pay interest on overdue principal and premium, if
any, and interest on overdue installments of interest, to the extent lawful, at
a rate per annum that is 13 7/8% per annum.

<PAGE>   95
                                      A-6

2. Method of Payment.

             The Company will pay principal as provided above and interest
(except defaulted interest) on the principal amount of the Notes as provided
above on each March 15 and September 15 to the Persons who are Holders (as
reflected in the Note Register at the close of business on such March 1 and
September 1, immediately preceding the Interest Payment Date), in each case,
even if the Note is cancelled on registration of transfer or registration of
exchange after such record date; provided that, with respect to the payment of
principal, the Company will not make payment to the Holder unless this Note is
surrendered to a Paying Agent.

             The Company will pay principal, premium, if any, and as provided
above, interest in the currency of the United States that at the time of payment
is legal tender for the payment of public and private debts. However, the
Company may pay principal, premium, if any, and interest by its check payable in
such currency. It may mail an interest check to a Holder's registered address
(as reflected in the Note Register). If a payment date is a date other than a
Business Day at a place of payment, payment may be made at that place on the
next succeeding day that is a Business Day and no interest shall accrue for the
intervening period.

3. Paying Agent and Registrar.

             Initially, the Trustee will act as Paying Agent and Registrar. The
Company may change any Paying Agent or Registrar without notice. The Company,
any Subsidiary or any Affiliate of any of them may act as Paying Agent,
Registrar or co-Registrar.

4. Indenture; Issuance of Additional Notes.

             This Note is one of a duly authorized issue of Notes of the Company
designated its 13 7/8% Senior Notes due 2010, issued and to be issued under an
Indenture, dated as of March 10, 2000 (the "Indenture"), between the Company and
the Trustee. Capitalized terms used herein are used as defined in the Indenture
unless otherwise indicated. The terms of the Notes include those stated in the
Indenture and those made part of the Indenture by reference to the Trust
Indenture Act. The Notes are subject to all such terms, and Holders are referred
to the Indenture and the Trust Indenture Act for a statement of all such terms.
To the extent permitted by applicable law, in the event of any inconsistency
between the terms of this Note and the terms of the Indenture, the terms of the
Indenture shall control.

5. Redemption.

             The Notes will be redeemable, at the Company's option, in whole or
in part, at any time and from time to time on or after March 15, 2005 and prior
to maturity, upon not less than 30 nor more than 60 days' prior notice mailed by
first-class mail to each Holders' last address as it appears in the Note
Register, at the following Redemption Prices (expressed in percentages of their

<PAGE>   96
                                      A-7

principal amount), plus accrued and unpaid interest, if any, to the Redemption
Date (subject to the right of Holders of record on the relevant Regular Record
Date that is on or prior to the Redemption Date to receive interest due on an
Interest Payment Date), if redeemed during the 12-month period commencing on
March 15 of the years set forth below:

<TABLE>
<CAPTION>
                                                          Redemption
                      Year                                   Price
                      ----                                ----------
<S>                                                        <C>
                      2005                                 106.938%
                      2006                                 104.625%
                      2007                                 102.313%
                      2008 and thereafter                  100.000%
</TABLE>

             In addition, at any time or from time to time on or prior to March
15, 2003, the Company may, at its option, redeem up to 35% of the aggregate
principal amount of the Notes with the net proceeds of one or more sales of
Capital Stock, at a Redemption Price (expressed as a percentage of principal
amount) of 113.875% plus accrued interest to the Redemption Date, provided, (i)
that Notes representing at least 65% of the aggregate principal amount of the
Notes originally issued remain outstanding after each such redemption and (ii)
that notice of each such redemption is mailed within 60 days of each such sale
of Capital Stock.

6. Notice of Redemption.

        Notice of any optional redemption will be mailed at least 30 days but
not more than 60 days before the Redemption Date to each Holder of Notes to be
redeemed at such Holder's last address as it appears in the Note Register. Notes
in original denominations larger than $1,000 of principal amount may be redeemed
in part. On and after the Redemption Date, interest ceases to accrue on Notes or
portions of Notes called for redemption, unless the Company defaults in the
payment of the Redemption Price.

7. Repurchase upon Change in Control.

        Upon the occurrence of any Change of Control, each Holder shall have the
right to require the repurchase of its Notes by the Company in cash pursuant to
the offer described in the Indenture at a purchase price equal to 101% of the
principal amount thereof plus accrued and unpaid interest, if any, to the date
of purchase (the "Change of Control Payment").

        A notice of such Change of Control will be mailed within 30 days after
any Change of Control occurs to each Holder at his last address as it appears in
the Note Register. Notes in original denominations larger than $1,000 of
principal amount may be sold to the Company in part. On and after the date of
the Change of Control Payment, interest ceases to accrue on Notes or portions of
Notes surrendered for purchase by the Company, unless the Company defaults in
the payment of the Change of Control Payment.

<PAGE>   97
                                      A-8

8. Registration Rights

        Pursuant to the Registration Rights Agreement, the Company will be
obligated, within 180 days after the issue date of this Note, to consummate an
exchange offer pursuant to which the Holder of this Note shall have the right to
exchange this Note for the Company's Exchange Notes (as defined in the
Registration Rights Agreement) which have been registered under the Securities
Act, in like principal amount and having terms identical in all material
respects as the initial Notes. The Holders of the initial Notes shall be
entitled to receive certain additional interest payments in the event such
exchange offer is not consummated and upon certain other conditions, all
pursuant and in accordance with the terms of the Registration Rights Agreement.

9. Denominations; Transfer; Exchange.

        The Notes are in registered form without coupons in denominations of
$1,000 of principal amount and any integral multiples of $1,000 in excess
thereof. A Holder may register the transfer or exchange of Notes in accordance
with the Indenture. The Registrar may require a Holder, among other things, to
furnish appropriate endorsements and transfer documents and to pay any taxes and
fees required by law or permitted by the Indenture. The Registrar need not
register the transfer or exchange of any Notes selected for redemption. Also, it
need not register the transfer or exchange of any Notes for a period of 15 days
before a selection of Notes to be redeemed is made.

10. Persons Deemed Owners.

        A Holder shall be treated as the owner of a Note for all purposes.

11. Unclaimed Money.

        If money for the payment of principal, premium, if any, or interest
remains unclaimed for two years, subject to applicable state escheatment laws,
the Trustee and the Paying Agent will pay the money back to the Company at its
request. After that, Holders entitled to the money must look to the Company for
payment, unless an abandoned property law designates another Person, and all
liability of the Trustee and such Paying Agent with respect to such money shall
cease.

12. Discharge Prior to Redemption or Maturity.

        If the Company deposits with the Trustee money and/or U.S. Government
Obligations sufficient, in the opinion of a nationally recognized independent
public accounting firm, to pay the then outstanding principal of, premium, if
any, and accrued interest on the Notes (a) to redemption or maturity, the
Company will be discharged from the Indenture and the Notes, except in certain
circumstances for certain sections thereof, and (b) to Stated Maturity, the
Company will be discharged from certain covenants set forth in the Indenture.

<PAGE>   98
                                      A-9

13. Amendment; Supplement; Waiver.

        Subject to certain exceptions, the Indenture or the Notes may be amended
or supplemented with the consent of the Holders of at least a majority in
principal amount of the Notes then outstanding, and any existing default or
compliance with any provision may be waived with the consent of the Holders of
at least a majority in principal amount of the Notes then outstanding. Without
notice to or the consent of any Holder, the parties thereto may amend or
supplement the Indenture or the Notes to, among other things, cure any
ambiguity, defect or inconsistency and make any change that does not materially
and adversely affect the rights of any Holder.

14. Restrictive Covenants.

        The Indenture imposes certain limitations on the ability of the Company
and its Restricted Subsidiaries, among other things, to Incur Indebtedness, make
Restricted Payments, use the proceeds from Asset Sales, engage in transactions
with Affiliates or, with respect to the Company, merge, consolidate or transfer
substantially all of its assets. Within 90 days after the end of the last fiscal
quarter of each year, the Company must report to the Trustee on compliance with
the terms of the Indenture.

15. Successor Persons.

        When a successor Person or other entity assumes all the obligations of
its predecessor under the Notes and the Indenture, the predecessor Person will
be released from those obligations.

16. Defaults and Remedies.

        The following events constitute "Events of Default" under the Indenture:
(a) default in the payment of principal of (or premium, if any, on) any Note
when the same becomes due and payable at maturity, upon acceleration, redemption
or otherwise; (b) default in the payment of interest on any Note when the same
becomes due and payable, and such default continues for a period of 30 days;
provided that a failure to make any of the first four scheduled interest
payments on the Notes within three business days after an interest payment date
will constitute an Event of Default with no grace or cure period; (c) default in
the performance or breach of the provisions of the Indenture applicable to
mergers, consolidations and transfers of all or substantially all of the assets
of the Company or the failure by the Company to make or consummate an Offer to
Purchase in accordance with Section 4.11 or Section 4.12; (d) the Company or any
Restricted Subsidiary defaults in the performance of or breaches any other
covenant or agreement in the Indenture or under the Notes (other than a default
specified in clause (a), (b) or (c) above) and such default or breach continues
for a period of 45 consecutive days after written notice by the Trustee or the
Holders of 25% or more in aggregate principal amount of the Notes; (e) the
default under any mortgage, indenture or instrument under which there may be
issued or by which there may be secured or evidenced any Indebtedness of the
Company or any of its Significant Subsidiaries (or the payment

<PAGE>   99
                                      A-10

of which is Guaranteed by the Company or any of its Significant Subsidiaries)
whether such Indebtedness or Guarantee now exists or is created after the
Closing Date, and either such Indebtedness is already due and payable or such
default results in the acceleration of such Indebtedness prior to its express
maturity and, in each case, the amount of any such Indebtedness, together with
the amount of any other such Indebtedness the maturity of which has been so
accelerated or which is already due and payable, aggregates $10 million or more;
(f) one or more judgments, orders or decrees for the payment of money in excess
of $10 million, individually or in the aggregate (net of applicable insurance
coverage which is acknowledged in writing by the insurer), shall be entered
against the Company or any of its Significant Subsidiaries or any of their
respective properties and shall not be discharged and there shall have been a
period of 60 days or more during which a stay of enforcement of such judgment or
order, by reason of pending appeal or otherwise, shall not be in effect; (g) a
court having jurisdiction in the premises enters a decree or order for: (i)
relief in respect of the Company or any Significant Subsidiary in an involuntary
case under any applicable bankruptcy, insolvency or other similar law now or
hereafter in effect, (ii) appointment of a receiver, liquidator, assignee,
custodian, trustee, sequestrator or similar official of the Company or any
Significant Subsidiary or for all or substantially all of the property and
assets of the Company or any Significant Subsidiary, or (iii) the winding up or
liquidation of the affairs of the Company or any Significant Subsidiary and, in
each case, such decree or order shall remain unstayed and in effect for a period
of 45 consecutive days; (h) the Company or any Significant Subsidiary (A)
commences a voluntary case under any applicable bankruptcy, insolvency or other
similar law now or hereafter in effect, or consents to the entry of an order for
relief in an involuntary case under any such law, (B) consents to the
appointment of or taking possession by a receiver, liquidator, assignee,
custodian, trustee, sequestrator or similar official of the Company or any
Significant Subsidiary or for all or substantially all of the property and
assets of the Company or any Significant Subsidiary or (C) effects any general
assignment for the benefit of creditors; or (i) the Pledge Agreement shall cease
to be in full force and effect or enforceable in accordance with its terms,
other than in accordance with its terms.

        If an Event of Default (other than an Event of Default specified in
clause (g) or (h) above that occurs with respect to the Company or a Significant
Subsidiary) occurs and is continuing under the Indenture, the Trustee or the
Holders of at least 25% in aggregate principal amount of the Notes, then
outstanding, by written notice to the Company (and to the Trustee if such notice
is given by the Holders), may, and the Trustee at the request of such Holders
shall, declare the principal amount of, premium, if any, and accrued interest on
the Notes to be immediately due and payable.

        If an Event of Default, as defined in the Indenture, occurs and is
continuing, the Trustee or the Holders of at least 25% in aggregate principal
amount of the Notes then outstanding may declare all the Notes to be due and
payable. If a bankruptcy or insolvency default with respect to the Company or
any Restricted Subsidiary occurs and is continuing, the Notes automatically
become due and payable. Holders may not enforce the Indenture or the Notes
except as provided in the Indenture. The Trustee may require indemnity
satisfactory to it before it enforces the

<PAGE>   100
                                      A-11

Indenture or the Notes. Subject to certain limitations, Holders of at least a
majority in principal amount of the Notes then outstanding may direct the
Trustee in its exercise of any trust or power.

17. Trustee Dealings with Company.

        The Trustee under the Indenture, in its individual or any other
capacity, may make loans to, accept deposits from and perform services for the
Company or its Affiliates and may otherwise deal with the Company or its
Affiliates as if it were not the Trustee.

18. No Recourse Against Others.

        No incorporator or any past, present or future partner, stockholder,
other equity holder, officer, director, employee or controlling person as such,
of the Company or of any successor Person shall have any liability for any
obligations of the Company under the Notes or the Indenture or for any claim
based on, in respect of or by reason of, such obligations or their creation.
Each Holder by accepting a Note waives and releases all such liability. The
waiver and release are part of the consideration for the issuance of the Notes.

19. Authentication.

        This Note shall not be valid until the Trustee or authenticating agent
signs the certificate of authentication on the other side of this Note.

20. Abbreviations.

        Customary abbreviations may be used in the name of a Holder or an
assignee, such as: TEN COM (= tenants in common), TEN ENT (= tenants by the
entireties), JT TEN (= joint tenants with right of survivorship and not as
tenants in common), CUST (= Custodian) and U/G/M/A (= Uniform Gifts to Minors
Act).

        THIS NOTE SHALL BE GOVERNED BY THE LAWS OF THE STATE OF NEW YORK.

        The Company will furnish to any Holder upon written request and without
charge a copy of the Indenture. Requests may be made to COLO.COM, 2000 Sierra
Point Parkway, Suite 601, Brisbane, CA 94005-1819, Attention: David H. Stanley.

<PAGE>   101
                                      A-12

                  SCHEDULE OF PRINCIPAL AMOUNT OF INDEBTEDNESS
                             EVIDENCED BY THIS NOTE

             The initial principal amount of indebtedness evidenced by this Note
shall be $ [_______]. The following decreases/increases in the principal amount
evidenced by this Note have been made:

<TABLE>
<CAPTION>
                 Decrease in   Increase in    Total Principal
                 Principal     Principal      Amount of this Global   Notation Made
Date of          Amount of     Amount of      Note Following such     by or on
Decrease/        this Global   this Global    Decrease/Increase       Behalf of
Increase         Note          Note                                   Trustee
---------------- ------------- -------------- ----------------------- ----------------------
<S>              <C>           <C>            <C>                     <C>

---------------- ------------- -------------- ----------------------- ----------------------

---------------- ------------- -------------- ----------------------- ----------------------

---------------- ------------- -------------- ----------------------- ----------------------

---------------- ------------- -------------- ----------------------- ----------------------

---------------- ------------- -------------- ----------------------- ----------------------

---------------- ------------- -------------- ----------------------- ----------------------

---------------- ------------- -------------- ----------------------- ----------------------

---------------- ------------- -------------- ----------------------- ----------------------

---------------- ------------- -------------- ----------------------- ----------------------

---------------- ------------- -------------- ----------------------- ----------------------

---------------- ------------- -------------- ----------------------- ----------------------

---------------- ------------- -------------- ----------------------- ----------------------

---------------- ------------- -------------- ----------------------- ----------------------

---------------- ------------- -------------- ----------------------- ----------------------

---------------- ------------- -------------- ----------------------- ----------------------

---------------- ------------- -------------- ----------------------- ----------------------

---------------- ------------- -------------- ----------------------- ----------------------
</TABLE>

<PAGE>   102
                                      A-13

                            [FORM OF TRANSFER NOTICE]

             FOR VALUE RECEIVED the undersigned registered holder hereby
sell(s), assign(s) and transfer(s) unto

Insert Taxpayer Identification No.

-------------------------------------------------------------------------
Please print or typewrite name and address including zip code of assignee

-------------------------------------------------------------------------
the within Note and all rights thereunder, hereby irrevocably constituting

and appointing                        attorney to transfer said Note on the
              ------------------------
books of the Company with full power of substitution in the premises.

                     [THE FOLLOWING PROVISION TO BE INCLUDED
                     ON ALL NOTES OTHER THAN EXCHANGE NOTES]

        In connection with any transfer of this Note occurring prior to the date
which is the earlier of (i) the date of an effective Registration or (ii) the
end of the period referred to in Rule 144(k) under the Securities Act, the
undersigned confirms that without utilizing any general solicitation or general
advertising that:

                                   [Check One]

[ ] (a) this Note is being transferred in compliance with the exemption
        from registration under the Securities Act of 1933, as amended, provided
        by Rule 144A thereunder.

                                       or

[ ] (b) this Note is being transferred other than in accordance with (a)
        above and documents are being furnished which comply with the conditions
        of transfer set forth in this Note and the Indenture.

If none of the foregoing boxes is checked, the Trustee or other Registrar shall
not be obligated to register this Note in the name of any Person other than the
Holder hereof unless and until the conditions to any such transfer of
registration set forth herein and in Section 2.08 of the Indenture shall have
been satisfied.

Date:
     ---------              --------------------------------------------

<PAGE>   103
                                      A-14

                                    NOTICE: The signature to this assignment
                                    must correspond with the name as written
                                    upon the face of the within-mentioned
                                    instrument in every particular, without
                                    alteration or any change whatsoever.

TO BE COMPLETED BY PURCHASER IF (a) ABOVE IS CHECKED.

        The undersigned represents and warrants that it is purchasing this Note
for its own account or an account with respect to which it exercises sole
investment discretion and that it and any such account is a "qualified
institutional buyer" within the meaning of Rule 144A under the Securities Act of
1933, as amended, and is aware that the sale to it is being made in reliance on
Rule 144A and acknowledges that it has received such information regarding the
Company as the undersigned has requested pursuant to Rule 144A or has determined
not to request such information and that it is aware that the transferor is
relying upon the undersigned's foregoing representations in order to claim the
exemption from registration provided by Rule 144A.

Dated:
      ------------------        -----------------------------------------------
                                NOTICE:  To be executed by an executive officer

<PAGE>   104
                                      A-15

                       OPTION OF HOLDER TO ELECT PURCHASE

             If you wish to have this Note purchased by the Company pursuant to
Section 4.11 or Section 4.12 of the Indenture, check the Box: [ ]

             If you wish to have a portion of this Note purchased by the Company
pursuant to Section 4.11 or Section 4.12 of the Indenture, state the amount (in
principal amount): $_____________.

Date:___________

Your Signature:_________________________________________________________________
              (Sign exactly as your name appears on the other side of this Note)

Signature Guarantee (by an institution that is a member of the Signature
Guarantee Medallion Program): ______________________________

<PAGE>   105

                                                                       EXHIBIT B
                            FORM OF CERTIFICATED NOTE

                                 [FACE OF NOTE]

THE SECURITIES EVIDENCED HEREBY HAVE NOT BEEN REGISTERED UNDER THE UNITED STATES
SECURITIES ACT OF 1933, AS AMENDED (THE "SECURITIES ACT"), AND MAY NOT BE
OFFERED, SOLD, PLEDGED OR OTHERWISE TRANSFERRED EXCEPT (1) TO A PERSON WHOM THE
SELLER REASONABLY BELIEVES IS A QUALIFIED INSTITUTIONAL BUYER WITHIN THE MEANING
OF RULE 144A UNDER THE SECURITIES ACT PURCHASING FOR ITS OWN ACCOUNT OR FOR THE
ACCOUNT OF A QUALIFIED INSTITUTIONAL BUYER IN A TRANSACTION MEETING THE
REQUIREMENTS OF RULE 144A, (2) PURSUANT TO AN EXEMPTION FROM REGISTRATION UNDER
THE SECURITIES ACT PROVIDED BY RULE 144 THEREUNDER (IF AVAILABLE), (3) TO AN
INSTITUTIONAL ACCREDITED INVESTOR IN A TRANSACTION EXEMPT FROM THE REGISTRATION
REQUIREMENTS UNDER REGULATION D UNDER THE SECURITIES ACT OR (4) PURSUANT TO AN
EFFECTIVE REGISTRATION STATEMENT UNDER THE SECURITIES ACT, IN EACH CASE, IN
ACCORDANCE WITH ALL APPLICABLE SECURITIES LAWS OF THE STATES OF THE UNITED
STATES.

THIS NOTE IS INITIALLY ISSUED AS PART OF AN ISSUANCE OF UNITS, EACH OF WHICH
CONSISTS OF ONE NOTE AND ONE WARRANT INITIALLY ENTITLING THE HOLDER THEREOF TO
PURCHASE 19.9718 SHARES OF COMMON STOCK, PAR VALUE $0.01 PER SHARE, OF COLO.COM
(A "WARRANT"). PRIOR TO THE CLOSE OF BUSINESS UPON THE EARLIEST TO OCCUR OF (i)
MARCH 10, 2001, (ii) 180 DAYS AFTER THE CLOSING DATE OF THE COMPANY'S INITIAL
PUBLIC OFFERING, (iii) THE COMMENCEMENT OF AN EXCHANGE OFFER WITH RESPECT TO THE
NOTES, (iv) THE EFFECTIVENESS OF A SHELF REGISTRATION STATEMENT WITH RESPECT TO
THE NOTES, (v) THE COMMENCEMENT OF AN OFFER TO PURCHASE THE NOTES UPON A CHANGE
OF CONTROL OR (vi) SUCH DATE AS DETERMINED BY GOLDMAN, SACHS & CO. IN ITS SOLE
DISCRETION, THE NOTES EVIDENCED BY THIS CERTIFICATE MAY NOT BE TRANSFERRED OR
EXCHANGED SEPARATELY FROM, BUT MAY BE TRANSFERRED OR EXCHANGED ONLY TOGETHER
WITH, THE WARRANTS.

<PAGE>   106
                                      B-2

                                    COLO.COM

                          13 7/8% Senior Note Due 2010

                                                        [CUSIP][CINS][ISIN][___]
No.  __________                                                       $[_______]

        Issue date: _______, ____

        COLO.COM, a California corporation (the "Company", which term includes
any successor under the Indenture hereinafter referred to), for value received,
promises to pay to ________________, or its registered assigns, upon surrender
hereof the principal sum of $___________ on March 15, 2010.

        Interest Payment Dates: March 15 and September 15, commencing September
15, 2000.

        Record Dates: March 1 and September 1.

        Reference is hereby made to the further provisions of this Note set
forth on the reverse hereof, which further provisions shall for all purposes
have the same effect as if set forth at this place.

<PAGE>   107

       IN WITNESS WHEREOF, the Company has caused this Note to be signed
manually or by facsimile by its duly authorized officers.

Date:  __________                        COLO.COM

                                         By
                                           ------------------------------------
                                             Name:
                                             Title:

                    (Trustee's Certificate of Authentication)

This is one of the 13 7/8% Senior Notes due 2010 described in the
within-mentioned Indenture.

Date:  _________                         STATE STREET BANK AND TRUST COMPANY
                                         OF CALIFORNIA, N.A., as Trustee

                                         By
                                           ------------------------------------
                                              Authorized Signatory

<PAGE>   108
                                      B-4

                             [REVERSE SIDE OF NOTE]

                                    COLO.COM

                          13 7/8% Senior Note due 2010

1. Principal and Interest.

             The Company will pay the principal of this Note on March 15, 2010.

             The Company promises to pay interest on the principal amount of
this Note on each Interest Payment Date, as set forth below, at the rate per
annum shown above.

             Interest will be payable semiannually in cash (to the holders of
record of the Notes at the close of business on the March 15 or September 15
immediately preceding the Interest Payment Date) on each Interest Payment Date,
commencing September 15, 2000. Interest will be computed on the basis of a
360-day year of twelve 30-day months.

             If an exchange offer registered under the Securities Act is not
consummated, and a shelf registration statement under the Securities Act with
respect to resales of the Notes is not declared effective by the Commission, on
or before the date that is six months after the Closing Date in accordance with
the terms of the Registration Rights Agreement, dated March 10, 2000, between
the Company and Goldman, Sachs & Co., as the manager for itself and the several
initial purchasers named on Schedule I to the Purchase Agreement, dated March 3,
2000, annual interest (in addition to interest otherwise due on the Notes) will
accrue, at an annual rate equal to 0.25% for the first 90 days thereafter, 0.50%
for the second 90 days thereafter, 0.75% for the third 90 days thereafter and
1.00% thereafter until the consummation of a registered exchange offer or the
effectiveness of a shelf-registration statement with respect to resale of this
Note. The Holder of this Note is entitled to the benefits of such Registration
Rights Agreement.

             The Holder of this Note is entitled to the benefits of a Pledge
Agreement, dated March 10, 2000, between the Company and State Street Bank and
Trust Company of California, N.A., as trustee (the "Trustee"), pursuant to which
the Company has placed in the Pledge Account cash or Government Securities
sufficient to provide for the payment of the first four interest payments on
this Note.

             The Company shall pay interest on overdue principal and premium, if
any, and interest on overdue installments of interest, to the extent lawful, at
a rate per annum that is 13 7/8% per annum.

<PAGE>   109
                                      B-5

2. Method of Payment.

             The Company will pay principal as provided above and interest
(except defaulted interest) on the principal amount of the Notes as provided
above on each March 15 and September 15 to the Persons who are Holders (as
reflected in the Note Register at the close of business on such March 1 and
September 1, immediately preceding the Interest Payment Date), in each case,
even if the Note is cancelled on registration of transfer or registration of
exchange after such record date; provided that, with respect to the payment of
principal, the Company will not make payment to the Holder unless this Note is
surrendered to a Paying Agent.

             The Company will pay principal, premium, if any, and as provided
above, interest in the currency of the United States that at the time of payment
is legal tender for the payment of public and private debts. However, the
Company may pay principal, premium, if any, and interest by its check payable in
such currency. It may mail an interest check to a Holder's registered address
(as reflected in the Note Register). If a payment date is a date other than a
Business Day at a place of payment, payment may be made at that place on the
next succeeding day that is a Business Day and no interest shall accrue for the
intervening period.

3. Paying Agent and Registrar.

             Initially, the Trustee will act as Paying Agent and Registrar. The
Company may change any Paying Agent or Registrar without notice. The Company,
any Subsidiary or any Affiliate of any of them may act as Paying Agent,
Registrar or co-Registrar.

4. Indenture; Issuance of Additional Notes.

             This Note is one of a duly authorized issue of Notes of the Company
designated its 13 7/8% Senior Notes due 2010, issued and to be issued under an
Indenture, dated as of March 10, 2000 (the "Indenture"), between the Company and
the Trustee. Capitalized terms used herein are used as defined in the Indenture
unless otherwise indicated. The terms of the Notes include those stated in the
Indenture and those made part of the Indenture by reference to the Trust
Indenture Act. The Notes are subject to all such terms, and Holders are referred
to the Indenture and the Trust Indenture Act for a statement of all such terms.
To the extent permitted by applicable law, in the event of any inconsistency
between the terms of this Note and the terms of the Indenture, the terms of the
Indenture shall control.

5. Redemption.

             The Notes will be redeemable, at the Company's option, in whole or
in part, at any time and from time to time on or after March 15, 2005 and prior
to maturity, upon not less than 30 nor more than 60 days' prior notice mailed by
first-class mail to each Holders' last address as it appears in the Note
Register, at the following Redemption Prices (expressed in percentages of their

<PAGE>   110
                                      B-6

principal amount), plus accrued and unpaid interest, if any, to the Redemption
Date (subject to the right of Holders of record on the relevant Regular Record
Date that is on or prior to the Redemption Date to receive interest due on an
Interest Payment Date), if redeemed during the 12-month period commencing on
March 15 of the years set forth below:

<TABLE>
<CAPTION>
                                                          Redemption
                      Year                                   Price
                      ----                                ----------
<S>                   <C>                                  <C>
                      2005                                 106.938%
                      2006                                 104.625%
                      2007                                 102.313%
                      2008 and thereafter                  100.000%
</TABLE>

             In addition, at any time or from time to time on or prior to March
15, 2003, the Company may, at its option, redeem up to 35% of the aggregate
principal amount of the Notes with the net proceeds of one or more sales of
Capital Stock, at a Redemption Price (expressed as a percentage of principal
amount) of 113.875% plus accrued interest to the Redemption Date, provided, (i)
that Notes representing at least 65% of the aggregate principal amount of the
Notes originally issued remain outstanding after each such redemption and (ii)
that notice of each such redemption is mailed within 60 days of each such sale
of Capital Stock.

6. Notice of Redemption.

             Notice of any optional redemption will be mailed at least 30 days
but not more than 60 days before the Redemption Date to each Holder of Notes to
be redeemed at such Holder's last address as it appears in the Note Register.
Notes in original denominations larger than $1,000 of principal amount may be
redeemed in part. On and after the Redemption Date, interest ceases to accrue on
Notes or portions of Notes called for redemption, unless the Company defaults in
the payment of the Redemption Price.

7. Repurchase upon Change in Control.

             Upon the occurrence of any Change of Control, each Holder shall
have the right to require the repurchase of its Notes by the Company in cash
pursuant to the offer described in the Indenture at a purchase price equal to
101% of the principal amount thereof plus accrued and unpaid interest, if any,
to the date of purchase (the "Change of Control Payment").

             A notice of such Change of Control will be mailed within 30 days
after any Change of Control occurs to each Holder at his last address as it
appears in the Note Register. Notes in original denominations larger than $1,000
of principal amount may be sold to the Company in part. On and after the date of
the Change of Control Payment, interest ceases to accrue on Notes or portions of
Notes surrendered for purchase by the Company, unless the Company defaults in
the payment of the Change of Control Payment.

<PAGE>   111
                                      B-7

8. Registration Rights

             Pursuant to the Registration Rights Agreement, the Company will be
obligated, within 180 days after the issue date of this Note, to consummate an
exchange offer pursuant to which the Holder of this Note shall have the right to
exchange this Note for the Company's Exchange Notes (as defined in the
Registration Rights Agreement) which have been registered under the Securities
Act, in like principal amount and having terms identical in all material
respects as the initial Notes. The Holders of the initial Notes shall be
entitled to receive certain additional interest payments in the event such
exchange offer is not consummated and upon certain other conditions, all
pursuant and in accordance with the terms of the Registration Rights Agreement.

9. Denominations; Transfer; Exchange.

             The Notes are in registered form without coupons in denominations
of $1,000 of principal amount and any integral multiples of $1,000 in excess
thereof. A Holder may register the transfer or exchange of Notes in accordance
with the Indenture. The Registrar may require a Holder, among other things, to
furnish appropriate endorsements and transfer documents and to pay any taxes and
fees required by law or permitted by the Indenture. The Registrar need not
register the transfer or exchange of any Notes selected for redemption. Also, it
need not register the transfer or exchange of any Notes for a period of 15 days
before a selection of Notes to be redeemed is made.

10. Persons Deemed Owners.

             A Holder shall be treated as the owner of a Note for all purposes.

11. Unclaimed Money.

             If money for the payment of principal, premium, if any, or interest
remains unclaimed for two years, subject to applicable state escheatment laws,
the Trustee and the Paying Agent will pay the money back to the Company at its
request. After that, Holders entitled to the money must look to the Company for
payment, unless an abandoned property law designates another Person, and all
liability of the Trustee and such Paying Agent with respect to such money shall
cease.

12. Discharge Prior to Redemption or Maturity.

             If the Company deposits with the Trustee money and/or U.S.
Government Obligations sufficient, in the opinion of a nationally recognized
independent public accounting firm, to pay the then outstanding principal of,
premium, if any, and accrued interest on the Notes (a) to redemption or
maturity, the Company will be discharged from the Indenture and the Notes,
except in certain circumstances for certain sections thereof, and (b) to Stated
Maturity, the Company will be discharged from certain covenants set forth in the
Indenture.

<PAGE>   112
                                      B-8

13. Amendment; Supplement; Waiver.

             Subject to certain exceptions, the Indenture or the Notes may be
amended or supplemented with the consent of the Holders of at least a majority
in principal amount of the Notes then outstanding, and any existing default or
compliance with any provision may be waived with the consent of the Holders of
at least a majority in principal amount of the Notes then outstanding. Without
notice to or the consent of any Holder, the parties thereto may amend or
supplement the Indenture or the Notes to, among other things, cure any
ambiguity, defect or inconsistency and make any change that does not materially
and adversely affect the rights of any Holder.

14. Restrictive Covenants.

             The Indenture imposes certain limitations on the ability of the
Company and its Restricted Subsidiaries, among other things, to Incur
Indebtedness, make Restricted Payments, use the proceeds from Asset Sales,
engage in transactions with Affiliates or, with respect to the Company, merge,
consolidate or transfer substantially all of its assets. Within 90 days after
the end of the last fiscal quarter of each year, the Company must report to the
Trustee on compliance with the terms of the Indenture.

15. Successor Persons.

             When a successor Person or other entity assumes all the obligations
of its predecessor under the Notes and the Indenture, the predecessor Person
will be released from those obligations.

16. Defaults and Remedies.

             The following events constitute "Events of Default" under the
Indenture: (a) default in the payment of principal of (or premium, if any, on)
any Note when the same becomes due and payable at maturity, upon acceleration,
redemption or otherwise; (b) default in the payment of interest on any Note when
the same becomes due and payable, and such default continues for a period of 30
days; provided that a failure to make any of the first four scheduled interest
payments on the Notes within three business days after an interest payment date
will constitute an Event of Default with no grace or cure period; (c) default in
the performance or breach of the provisions of the Indenture applicable to
mergers, consolidations and transfers of all or substantially all of the assets
of the Company or the failure by the Company to make or consummate an Offer to
Purchase in accordance with Section 4.11 or Section 4.12; (d) the Company or any
Restricted Subsidiary defaults in the performance of or breaches any other
covenant or agreement in the Indenture or under the Notes (other than a default
specified in clause (a), (b) or (c) above) and such default or breach continues
for a period of 45 consecutive days after written notice by the Trustee or the
Holders of 25% or more in aggregate principal amount of the Notes; (e) the
default under any mortgage, indenture or instrument under which there may be
issued or by which there may be secured or evidenced any Indebtedness of the
Company or any of its Significant Subsidiaries (or the payment

<PAGE>   113
                                      B-9

of which is Guaranteed by the Company or any of its Significant Subsidiaries)
whether such Indebtedness or Guarantee now exists or is created after the
Closing Date, and either such Indebtedness is already due and payable or such
default results in the acceleration of such Indebtedness prior to its express
maturity and, in each case, the amount of any such Indebtedness, together with
the amount of any other such Indebtedness the maturity of which has been so
accelerated or which is already due and payable, aggregates $10 million or more;
(f) one or more judgments, orders or decrees for the payment of money in excess
of $10 million, individually or in the aggregate (net of applicable insurance
coverage which is acknowledged in writing by the insurer), shall be entered
against the Company or any of its Significant Subsidiaries or any of their
respective properties and shall not be discharged and there shall have been a
period of 60 days or more during which a stay of enforcement of such judgment or
order, by reason of pending appeal or otherwise, shall not be in effect; (g) a
court having jurisdiction in the premises enters a decree or order for: (i)
relief in respect of the Company or any Significant Subsidiary in an involuntary
case under any applicable bankruptcy, insolvency or other similar law now or
hereafter in effect, (ii) appointment of a receiver, liquidator, assignee,
custodian, trustee, sequestrator or similar official of the Company or any
Significant Subsidiary or for all or substantially all of the property and
assets of the Company or any Significant Subsidiary, or (iii) the winding up or
liquidation of the affairs of the Company or any Significant Subsidiary and, in
each case, such decree or order shall remain unstayed and in effect for a period
of 45 consecutive days; (h) the Company or any Significant Subsidiary (A)
commences a voluntary case under any applicable bankruptcy, insolvency or other
similar law now or hereafter in effect, or consents to the entry of an order for
relief in an involuntary case under any such law, (B) consents to the
appointment of or taking possession by a receiver, liquidator, assignee,
custodian, trustee, sequestrator or similar official of the Company or any
Significant Subsidiary or for all or substantially all of the property and
assets of the Company or any Significant Subsidiary or (C) effects any general
assignment for the benefit of creditors; or (i) the Pledge Agreement shall cease
to be in full force and effect or enforceable in accordance with its terms,
other than in accordance with its terms.

             If an Event of Default (other than an Event of Default specified in
clause (g) or (h) above that occurs with respect to the Company or a Significant
Subsidiary) occurs and is continuing under the Indenture, the Trustee or the
Holders of at least 25% in aggregate principal amount of the Notes, then
outstanding, by written notice to the Company (and to the Trustee if such notice
is given by the Holders) , may, and the Trustee at the request of such Holders
shall, declare the principal amount of, premium, if any, and accrued interest on
the Notes to be immediately due and payable.

             If an Event of Default, as defined in the Indenture, occurs and is
continuing, the Trustee or the Holders of at least 25% in aggregate principal
amount of the Notes then outstanding may declare all the Notes to be due and
payable. If a bankruptcy or insolvency default with respect to the Company or
any Restricted Subsidiary occurs and is continuing, the Notes automatically
become due and payable. Holders may not enforce the Indenture or the Notes
except as provided in the Indenture. The Trustee may require indemnity
satisfactory to it before it enforces the

<PAGE>   114
                                      B-10

Indenture or the Notes. Subject to certain limitations, Holders of at least a
majority in principal amount of the Notes then outstanding may direct the
Trustee in its exercise of any trust or power.

17. Trustee Dealings with Company.

             The Trustee under the Indenture, in its individual or any other
capacity, may make loans to, accept deposits from and perform services for the
Company or its Affiliates and may otherwise deal with the Company or its
Affiliates as if it were not the Trustee.

18. No Recourse Against Others.

             No incorporator or any past, present or future partner,
stockholder, other equity holder, officer, director, employee or controlling
person as such, of the Company or of any successor Person shall have any
liability for any obligations of the Company under the Notes or the Indenture or
for any claim based on, in respect of or by reason of, such obligations or their
creation. Each Holder by accepting a Note waives and releases all such
liability. The waiver and release are part of the consideration for the issuance
of the Notes.

19. Authentication.

             This Note shall not be valid until the Trustee or authenticating
agent signs the certificate of authentication on the other side of this Note.

20. Abbreviations.

             Customary abbreviations may be used in the name of a Holder or an
assignee, such as: TEN COM (= tenants in common), TEN ENT (= tenants by the
entireties), JT TEN (= joint tenants with right of survivorship and not as
tenants in common), CUST (= Custodian) and U/G/M/A (= Uniform Gifts to Minors
Act).

             THIS NOTE SHALL BE GOVERNED BY THE LAWS OF THE STATE OF NEW YORK.

             The Company will furnish to any Holder upon written request and
without charge a copy of the Indenture. Requests may be made to COLO.COM, 2000
Sierra Point Parkway, Suite 601, Brisbane, CA 94005-1819, Attention: David H.
Stanley.

<PAGE>   115
                                      B-11

                            [FORM OF TRANSFER NOTICE]

             FOR VALUE RECEIVED the undersigned registered holder hereby
sell(s), assign(s) and transfer(s) unto

Insert Taxpayer Identification No.

-------------------------------------------------------------------------
Please print or typewrite name and address including zip code of assignee

-------------------------------------------------------------------------
the within Note and all rights thereunder, hereby irrevocably constituting

and appointing                        attorney to transfer said Note on the
              ------------------------
books of the Company with full power of substitution in the premises.

                     [THE FOLLOWING PROVISION TO BE INCLUDED
                     ON ALL NOTES OTHER THAN EXCHANGE NOTES]

        In connection with any transfer of this Note occurring prior to the date
which is the earlier of (i) the date of an effective Registration or (ii) the
end of the period referred to in Rule 144(k) under the Securities Act, the
undersigned confirms that without utilizing any general solicitation or general
advertising that:

                                   [Check One]

[ ] (a) this Note is being transferred in compliance with the exemption
        from registration under the Securities Act of 1933, as amended, provided
        by Rule 144A thereunder.

                                       or

[ ] (b) this Note is being transferred other than in accordance with (a)
        above and documents are being furnished which comply with the conditions
        of transfer set forth in this Note and the Indenture.

If none of the foregoing boxes is checked, the Trustee or other Registrar shall
not be obligated to register this Note in the name of any Person other than the
Holder hereof unless and until the conditions to any such transfer of
registration set forth herein and in Section 2.08 of the Indenture shall have
been satisfied.

Date:
     ---------              --------------------------------------------

<PAGE>   116
\                                      B-12

                                    NOTICE: The signature to this assignment
                                    must correspond with the name as written
                                    upon the face of the within-mentioned
                                    instrument in every particular, without
                                    alteration or any change whatsoever.

TO BE COMPLETED BY PURCHASER IF (a) ABOVE IS CHECKED.

        The undersigned represents and warrants that it is purchasing this Note
for its own account or an account with respect to which it exercises sole
investment discretion and that it and any such account is a "qualified
institutional buyer" within the meaning of Rule 144A under the Securities Act of
1933, as amended, and is aware that the sale to it is being made in reliance on
Rule 144A and acknowledges that it has received such information regarding the
Company as the undersigned has requested pursuant to Rule 144A or has determined
not to request such information and that it is aware that the transferor is
relying upon the undersigned's foregoing representations in order to claim the
exemption from registration provided by Rule 144A.

Dated:
       ---------------------     -----------------------------------------------
                                 NOTICE:  To be executed by an executive officer

<PAGE>   117
                                      B-13

                       OPTION OF HOLDER TO ELECT PURCHASE

             If you wish to have this Note purchased by the Company pursuant to
Section 4.11 or Section 4.12 of the Indenture, check the Box: [ ]

             If you wish to have a portion of this Note purchased by the Company
pursuant to Section 4.11 or Section 4.12 of the Indenture, state the amount (in
principal amount): $______________.

Date:
     ---------------

Your Signature:
              -----------------------------------------------------------------
              (Sign exactly as your name appears on the other side of this Note)

Signature Guarantee (by an institution that is a member of the Signature
Guarantee Medallion Program): ______________________________

<PAGE>   118

                                                                       EXHIBIT C

                            Form of Certificate to Be
                          Delivered in Connection with
             Transfers to Non-QIB Institutional Accredited Investors

State Street Bank and Trust                                               [DATE]
Company of California, N.A.
633 West 5th Street,
12th Floor
Los Angeles, CA 90071
Attention:  Corporate Trust Department

                          Re: COLO.COM (the "Company")
                                [ ]% Senior Notes
                             due 2010 (the "Notes")

Dear Sirs:

             In connection with our proposed purchase of $___________ aggregate
principal amount of the Notes, we confirm that:

             1. We understand that any subsequent transfer of the Notes is
        subject to certain restrictions and conditions set forth in the
        Indenture dated as of __________, 2000 relating to the Notes (the
        "Indenture") and the undersigned agrees to be bound by, and not to
        resell, pledge or otherwise transfer the Notes except in compliance
        with, such restrictions and conditions and the Securities Act of 1933,
        as amended (the "Securities Act").

             2. We understand that the offer and sale of the Notes have not been
        registered under the Securities Act, and that the Notes may not be
        reoffered, resold, pledged or otherwise transferred except as permitted
        in the following sentence. We agree, on our own behalf and on behalf of
        any accounts for which we are acting as hereinafter stated, that if we
        should sell any Notes, we will do so only (A) (i) to a person whom we
        reasonable believe is "qualified institutional buyer" in a transaction
        meeting the requirements of Rule 144A under the Securities Act, (ii)
        pursuant to an exemption from registration under the Securities Act
        provided by Rule 144 thereunder, (iii) an institutional accredited
        investor exempted from the registration requirements under Regulation D
        under the Securities Act and (B) in accordance with all applicable
        securities laws of the states of the United States, and we further agree
        to

<PAGE>   119

        provide to any person purchasing any of the Notes from us a notice
        advising such purchaser that resales of the Notes are restricted as
        stated herein.

             3. We understand that, on any proposed resale of any Notes, we will
        be required to furnish to you and the Company such certifications, legal
        opinions and other information as you and the Company may reasonably
        require to confirm that the proposed sale complies with the foregoing
        restrictions. We further understand that the Notes purchased by us will
        bear a legend to the foregoing effect.

             4. We are an institutional "accredited investor" (as defined in
        Rule 501(a)(1), (2), (3) or (7) of Regulation D under the Securities
        Act) and have such knowledge and experience in financial and business
        matters as to be capable of evaluating the merits and risks of our
        investment in the Notes, and we and any accounts for which we are acting
        are each able to bear the economic risk of our or its investment.

             5. We are acquiring the Notes purchased by us for our own account
        or for one or more accounts (each of which is an institutional
        "accredited investor") as to each of which we exercise sole investment
        discretion.

             You and the Company are entitled to rely upon this letter and are
irrevocably authorized to produce this letter or a copy hereof to any interested
party in any administrative or legal proceedings or official inquiry with
respect to the matters covered hereby.

                                       Very truly yours,

                                       [Name of Transferee]

                                       By:
                                          ------------------------------------
                                       Authorized Signature

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