Document:

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                                                                     EXHIBIT 4.3

                                                                  Execution Copy

                                    COLO.COM

                          13 7/8% SENIOR NOTES DUE 2010

                          REGISTRATION RIGHTS AGREEMENT
                                                                  March 10, 2000

Goldman, Sachs & Co.,
Bear, Stearns & Co. Inc.
Chase Securities Inc.
Deutsche Bank Securities Inc.
Warburg Dillon Read LLC
Jefferies & Company, Inc.
  As representatives of the several Purchasers
  named in Schedule I to the Purchase Agreement
c/o Goldman, Sachs & Co.
85 Broad Street
New York, New York  10004

Ladies and Gentlemen:

        COLO.COM, a California corporation (the "Company"), proposes to issue
and sell to the Purchasers (as defined herein) upon the terms set forth in the
Purchase Agreement (as defined herein) its 13 7/8% Senior Notes due 2010. As an
inducement to the Purchasers to enter into the Purchase Agreement and in
satisfaction of a condition to the obligations of the Purchasers thereunder, the
Company agrees with the Purchasers for the benefit of holders (as defined
herein) from time to time of the Transfer Restricted Securities (as defined
herein) as follows:

               1. Certain Definitions. For purposes of this Registration Rights
Agreement, the following terms shall have the following respective meanings:

               "Base Interest" means the interest that would otherwise accrue on
the Securities under the terms thereof and the Indenture, without giving effect
to the provisions of this Agreement.

               The term "broker-dealer" means any broker or dealer registered
with the Commission under the Exchange Act.

               "Closing Date" means the date on which the Securities are
initially issued.

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               "Commission" means the United States Securities and Exchange
Commission, or any other federal agency at the time administering the Exchange
Act or the Securities Act, whichever is the relevant statute for the particular
purpose.

               "Effective Time," in the case of (i) an Exchange Registration,
means the time and date as of which the Commission declares the Exchange
Registration Statement effective or as of which the Exchange Registration
Statement otherwise becomes effective and (ii) a Shelf Registration, means the
time and date as of which the Commission declares the Shelf Registration
Statement effective or as of which the Shelf Registration Statement otherwise
becomes effective.

               "Electing Holder" means any holder of Transfer Restricted
Securities that has returned a completed and signed Notice and Questionnaire to
the Company in accordance with Section 3(d)(ii) or 3(d)(iii) hereof.

               "Exchange Act" means the Securities Exchange Act of 1934, or any
successor thereto, as the same shall be amended from time to time.

               "Exchange Offer" has the meaning assigned thereto in Section 2(a)
hereof.

               "Exchange Registration" has the meaning assigned thereto in
Section 3(c) hereof.

               "Exchange Registration Statement" has the meaning assigned
thereto in Section 2(a) hereof.

               "Exchange Securities" has the meaning assigned thereto in Section
2(a) hereof.

               The term "holder" means each of the Purchasers and other Persons
who acquire Transfer Restricted Securities from time to time (including any
successors or assigns), in each case for so long as such Person owns any
Transfer Restricted Securities.

               "Indenture" means the Indenture, dated as of March 10, 2000,
between the Company and State Street Bank and Trust Company of California, N.A.,
as Trustee, as the same shall be amended from time to time.

               "Notice and Questionnaire" means a Notice of Registration
Statement and Selling Securityholder Questionnaire substantially in the form of
Exhibit A hereto.

               "Person" means a corporation, association, partnership,
organization, business, individual, government or political subdivision thereof
or governmental agency.

               "Purchase Agreement" means the Purchase Agreement, dated as of
March 3, 2000, between the Purchasers and the Company relating to the
Securities.

               "Purchasers" means the Purchasers named in Schedule I to the
Purchase Agreement.

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               "Registration Default" has the meaning assigned thereto in
Section 2(c) hereof.

               "Registration Expenses" has the meaning assigned thereto in
Section 4 hereof.

               "Resale Period" has the meaning assigned thereto in Section 2(a)
hereof.

               "Restricted Holder" means a holder that (i) is prohibited by law
or by Commission policy from participating in the Exchange Offer; (ii) may not
resell the Exchange Securities acquired by it in the Exchange Offer to the
public without delivering a prospectus and the prospectus contained in the
Exchange Registration Statement is not appropriate or available for such
resales; or (iii) is a broker-dealer and owns Securities acquired directly from
the Company or an affiliate of the Company.

               "Rule 144," "Rule 405" and "Rule 415" means, in each case, such
rule promulgated under the Securities Act (or any successor provision), as the
same shall be amended from time to time.

               "Securities" means, collectively, the 13 7/8% Senior Notes due
2010 of the Company to be issued and sold to the Purchasers, and securities
issued in exchange therefor or in lieu thereof pursuant to the Indenture.

               "Securities Act" means the Securities Act of 1933, or any
successor thereto, as the same shall be amended from time to time.

               "Shelf Registration" has the meaning assigned thereto in Section
2(b) hereof.

               "Shelf Registration Statement" has the meaning assigned thereto
in Section 2(b) hereof.

               "Special Interest" has the meaning assigned thereto in Section
2(c) hereof.

               "Transfer Restricted Securities" means each Security until (i)
the date on which such Security has been exchanged by a Person other than a
broker-dealer for an Exchange Security in the Exchange Offer; (ii) following the
exchange by a broker-dealer in the Exchange Offer of a Security for an Exchange
Security, until the date on which such Exchange Security is sold to a purchaser
who receives from such broker-dealer on or prior to the date of such sale a copy
of the prospectus contained in the Exchange Registration Statement; (iii) the
date on which such Security has been effectively registered under the Securities
Act and disposed of in accordance with the Self Registration Statement; or (iv)
the date on which such Security is, or may be, distributed to the public
pursuant to Rule 144 under the Securities Act.

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               "Trust Indenture Act" means the Trust Indenture Act of 1939, or
any successor thereto, and the rules, regulations and forms promulgated
thereunder, all as the same shall be amended from time to time.

        Unless the context otherwise requires, any reference herein to a
"Section" or "clause" refers to a Section or clause, as the case may be, of this
Registration Rights Agreement, and the words "herein," "hereof" and "hereunder"
and other words of similar import refer to this Registration Rights Agreement as
a whole and not to any particular Section or other subdivision.

               2. Registration Under the Securities Act. (a) Except as set forth
in Section 2(b) below, the Company agrees to use its commercially reasonable
efforts to file under the Securities Act, as soon as practicable, but no later
than 90 days after the Closing Date, a registration statement relating to an
offer to exchange (such registration statement, the "Exchange Registration
Statement", and such offer, the "Exchange Offer") any and all of the Securities
for a like aggregate principal amount of debt securities issued by the Company,
which debt securities are substantially identical to the Securities (and are
entitled to the benefits of a trust indenture which is substantially identical
to the Indenture or is the Indenture and which has been qualified under the
Trust Indenture Act), except that they have been registered pursuant to an
effective registration statement under the Securities Act and do not contain
provisions for the additional interest contemplated in Section 2(c) below (such
new debt securities hereinafter called "Exchange Securities"); provided that if
at the end of such 90-day period the Company has filed with the Commission a
registration statement with respect to an initial public offering of its common
stock which has not been declared effective by the Commission at such time, the
Company will have an additional 30 days to file an Exchange Registration
Statement. The Company agrees to use its commercially reasonable efforts to
cause the Exchange Registration Statement to become effective under the
Securities Act as soon as practicable, but not later than 180 days after the
Closing Date; provided that if the proviso of the preceding sentence is
applicable, then the Company shall have an additional 30 days to have the
Exchange Registration Statement declared effective. The Exchange Offer will be
registered under the Securities Act on the appropriate form and will comply with
all applicable tender offer rules and regulations under the Exchange Act.

               The Company further agrees to use its commercially reasonable
efforts to complete the Exchange Offer on or prior to 30 business days, or
longer, if required by the federal securities laws, after the date on which the
Exchange Registration Statement is declared effective by the Commission. The
Exchange Offer will be deemed to have been "completed" only if the debt
securities received by holders other than Restricted Holders in the Exchange
Offer for Transfer Restricted Securities are, upon receipt, transferable by each
such holder without restriction under the Securities Act and the Exchange Act
and without material restrictions under the blue sky or securities laws of a
substantial majority of the States of the United States of America. The Exchange
Offer shall be deemed to have been completed upon the earlier to occur of (i)
the Company having exchanged the Exchange Securities for all outstanding
Transfer Restricted Securities pursuant to the Exchange Offer and (ii) the
Company having exchanged, pursuant to the Exchange Offer, Exchange Securities
for all Transfer Restricted Securities that

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have been properly tendered and not withdrawn before the expiration of the
Exchange Offer, which shall be on a date that is at least 30 days following the
commencement of the Exchange Offer. Upon the request of any of the Purchasers,
the Company agrees (x) to include in the Exchange Registration Statement a
prospectus for use in any resales by any holder of Exchange Securities that is a
broker-dealer and (y) to keep such Exchange Registration Statement effective for
a period (the "Resale Period") beginning when Exchange Securities are first
issued in the Exchange Offer and ending upon the earlier of the expiration of
the 180th day after the Exchange Offer has been completed or such time as such
broker-dealers no longer own any Transfer Restricted Securities. With respect to
such Exchange Registration Statement, such holders shall have the benefit of the
rights of indemnification and contribution set forth in Sections 6(a), (c), (d)
and (e) hereof.

               (b) If (i) the Company is not permitted to consummate the
Exchange Offer because the Exchange Offer is not permitted by applicable law or
Commission policy or (ii) any holder of Securities notifies the Company prior to
the 20th day following consummation of the Exchange Offer that such holder is a
Restricted Holder, the Company shall, in lieu of (or, in the case of clause
(ii), in addition to) conducting the Exchange Offer contemplated by Section
2(a), use its commercially reasonable efforts to file under the Securities Act
as soon as practicable, but not later than 60 days after the time such
obligation to file arises (but in no event earlier than 90 days (or, in the
event the proviso of the first sentence of Section 2(a) is applicable, 120 days)
after the Closing Date), a "shelf" registration statement providing for the
registration of, and the sale on a continuous or delayed basis by the holders
of, all Transfer Restricted Securities, pursuant to Rule 415 or any similar rule
that may be adopted by the Commission (such filing, the "Shelf Registration" and
such registration statement, the "Shelf Registration Statement").

               The Company agrees to use its commercially reasonable efforts (x)
to cause the Shelf Registration Statement to become or be declared effective as
soon as practicable, but not later than 150 days after such obligation arises
(but in no event earlier than 180 days (or, in the event that the proviso in the
first sentence of Section 2(a) is applicable, 210 days) after the Closing Date)
and to keep such Shelf Registration Statement continuously effective for a
period ending on the earlier of the second anniversary of the Effective Time or
such time as there are no longer any Transfer Restricted Securities outstanding,
except during a period that a material nonpublic transaction would be required
to disclosed in the Shelf Registration Statement under the Securities Act and
the rules and regulations promulgated thereunder and such disclosure would have
adverse effects on business of the Company (provided that such period shall not
exceed 30 consecutive business days), provided, however, that no holder shall be
entitled to be named as a selling securityholder in the Shelf Registration
Statement or to use the prospectus forming a part thereof for resales of
Transfer Restricted Securities unless such holder is an Electing Holder, and (y)
after the Effective Time of the Shelf Registration Statement, promptly upon the
request of any holder of Transfer Restricted Securities that is not then an
Electing Holder, to take any action reasonably necessary to enable such holder
to use the prospectus forming a part thereof for resales of Transfer Restricted
Securities, including, without limitation, any action necessary to identify such
holder as a selling securityholder in the Shelf Registration Statement,
provided, however, that nothing in this Clause (y) shall relieve any such holder
of the

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obligation to return a completed and signed Notice and Questionnaire to the
Company in accordance with Section 3(d)(iii) hereof. The Company further agrees
to supplement or make amendments to the Shelf Registration Statement, as and
when required by the rules, regulations or instructions applicable to the
registration form used by the Company for such Shelf Registration Statement or
by the Securities Act or rules and regulations thereunder for shelf
registration, and the Company agrees to furnish to each Electing Holder copies
of any such supplement or amendment prior to its being used or promptly
following its filing with the Commission.

               (c) In the event that (i) the Company has not filed the Exchange
Registration Statement or Shelf Registration Statement on or before the date on
which such registration statement is required to be filed pursuant to Section
2(a) or 2(b), respectively, or (ii) such Exchange Registration Statement or
Shelf Registration Statement has not become effective or been declared effective
by the Commission on or before the date on which such registration statement is
required to become or be declared effective pursuant to Section 2(a) or 2(b),
respectively, or (iii) the Company fails to consummate the Exchange Offer within
30 business days of the date of effectiveness of the Exchange Registration
Statement (other than with respect to any Securities for which the holder has
failed to tender) or (iv) any Shelf Registration Statement or the Exchange
Registration Statement required by Section 2(a) or 2(b) hereof is filed and
declared effective but thereafter ceases to be effective or usable in connection
with resales of Transfer Restricted Securities during the periods specified in
Section 2(a) or 2(b) hereof (each such event referred to in clauses (i) through
(iv), a "Registration Default" and each period during which a Registration
Default has occurred and is continuing, a "Registration Default Period"), then,
as liquidated damages for such Registration Default, subject to the provisions
of Section 9(b), special interest ("Special Interest"), in addition to the Base
Interest, shall accrue at a per annum rate of 0.25% for the first 90 days of the
Registration Default Period, at a per annum rate of 0.50% for the second 90 days
of the Registration Default Period, at a per annum rate of 0.75% for the third
90 days of the Registration Default Period and at a per annum rate of 1.00%
thereafter for the remaining portion of the Registration Default Period. The
Special Interest shall be payable in cash semiannually in arrears on each
Interest Payment Date (as defined in the Indenture).

               (d) The Company shall take all actions necessary or advisable to
be taken by it to ensure that the transactions contemplated herein are effected
as so contemplated.

               (e) Any reference herein to a registration statement as of any
time shall be deemed to include any document incorporated, or deemed to be
incorporated, therein by reference as of such time and any reference herein to
any post-effective amendment to a registration statement as of any time shall be
deemed to include any document incorporated, or deemed to be incorporated,
therein by reference as of such time.

               3. Registration Procedures. If the Company files a registration
statement pursuant to Section 2(a) or Section 2(b), the following provisions
shall apply:

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                (a) At or before the Effective Time of the Exchange Offer or the
        Shelf Registration, as the case may be, the Company shall qualify the
        Indenture under the Trust Indenture Act of 1939.

                (b) In the event that such qualification would require the
        appointment of a new trustee under the Indenture, the Company shall
        appoint a new trustee thereunder pursuant to the applicable provisions
        of the Indenture.

                (c) In connection with the Company's obligations with respect to
        the registration of Exchange Securities as contemplated by Section 2(a)
        (the "Exchange Registration"), if applicable, the Company shall, as soon
        as practicable (or as otherwise specified):

                    (i) prepare and file with the Commission, as soon as
                reasonably practicable but in any case within the time periods
                specified in Section 2(a), an Exchange Registration Statement on
                any form which may be utilized by the Company and which shall
                permit the Exchange Offer and resales of Exchange Securities by
                broker-dealers during the Resale Period to be effected as
                contemplated by Section 2(a), and use its commercially
                reasonable efforts to cause such Exchange Registration Statement
                to become effective as soon as practicable but in any case
                within the time periods specified in Section 2(a);

                    (ii) as soon as reasonably practicable prepare and file with
                the Commission such amendments and supplements to such Exchange
                Registration Statement and the prospectus included therein as
                may be necessary to effect and maintain the effectiveness of
                such Exchange Registration Statement for the periods and
                purposes contemplated in Section 2(a) hereof and as may be
                required by the applicable rules and regulations of the
                Commission and the instructions applicable to the form of such
                Exchange Registration Statement, and promptly provide each
                broker-dealer holding Exchange Securities with such number of
                copies of the prospectus included therein (as then amended or
                supplemented), in conformity in all material respects with the
                requirements of the Securities Act and the Trust Indenture Act
                and the rules and regulations of the Commission thereunder, as
                such broker-dealer reasonably may request prior to the
                expiration of the Resale Period, for use in connection with
                resales of Exchange Securities;

                    (iii) promptly notify each broker-dealer that has requested
                or received copies of the prospectus included in such
                registration statement, and confirm such advice in writing, (A)
                when such Exchange Registration Statement or the prospectus
                included therein or any prospectus amendment or supplement or
                post-effective amendment has been filed, and, with respect to
                such Exchange Registration Statement or any post-effective
                amendment, when the same has become effective, (B) of any
                comments by the Commission and by the blue sky or securities
                commissioner or regulator of any state with respect thereto or
                any

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                request by the Commission for amendments or supplements to such
                Exchange Registration Statement or prospectus or for additional
                information, (C) of the issuance by the Commission of any stop
                order suspending the effectiveness of such Exchange Registration
                Statement or the initiation or threatening of any proceedings
                for that purpose, (D) if at any time the representations and
                warranties of the Company contemplated by Section 5 cease to be
                true and correct in all material respects, (E) of the receipt by
                the Company of any notification with respect to the suspension
                of the qualification of the Exchange Securities for sale in any
                jurisdiction or the initiation or threatening of any proceeding
                for such purpose, or (F) at any time during the Resale Period
                when a prospectus is required to be delivered under the
                Securities Act, that such Exchange Registration Statement,
                prospectus, prospectus amendment or supplement or post-effective
                amendment does not conform in all material respects to the
                applicable requirements of the Securities Act and the Trust
                Indenture Act and the rules and regulations of the Commission
                thereunder or contains an untrue statement of a material fact or
                omits to state any material fact required to be stated therein
                or necessary to make the statements therein not misleading in
                light of the circumstances then existing;

                    (iv) in the event that the Company would be required,
                pursuant to Section 3(e)(iii)(F) above, to notify any
                broker-dealers holding Exchange Securities, without delay
                prepare and furnish to each such holder a reasonable number of
                copies of a prospectus supplemented or amended so that, as
                thereafter delivered to purchasers of such Exchange Securities
                during the Resale Period, such prospectus shall conform in all
                material respects to the applicable requirements of the
                Securities Act and the Trust Indenture Act and the rules and
                regulations of the Commission thereunder and shall not contain
                an untrue statement of a material fact or omit to state a
                material fact required to be stated therein or necessary to make
                the statements therein not misleading in light of the
                circumstances then existing;

                    (v) use its commercially reasonable efforts to obtain the
                withdrawal of any order suspending the effectiveness of such
                Exchange Registration Statement or any post-effective amendment
                thereto at the earliest practicable date;

                    (vi) use its commercially reasonable efforts to (A) register
                or qualify the Exchange Securities under the securities laws or
                blue sky laws of such jurisdictions as are contemplated by
                Section 2(a) no later than the commencement of the Exchange
                Offer, (B) keep such registrations or qualifications in effect
                and comply with such laws so as to permit the continuance of
                offers, sales and dealings therein in such jurisdictions until
                the expiration of the Resale Period and (C) take any and all
                other actions as may be reasonably necessary or advisable to
                enable each broker-dealer holding Exchange Securities to
                consummate the disposition thereof in such jurisdictions;
                provided, however, that the Company

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                shall not be required for any such purpose to (1) qualify as a
                foreign corporation in any jurisdiction wherein it would not
                otherwise be required to qualify but for the requirements of
                this Section 3(c)(vi), (2) consent to general service of process
                in any such jurisdiction or (3) make any changes to its
                certificate of incorporation or by-laws or any agreement between
                it and its stockholders;

                    (vii) use its commercially reasonable efforts to obtain the
                consent or approval of each governmental agency or authority,
                whether federal, state or local, which may be required to effect
                the Exchange Registration, the Exchange Offer and the offering
                and sale of Exchange Securities by broker-dealers during the
                Resale Period;

                    (viii) provide a CUSIP number for all Exchange Securities,
                not later than the applicable Effective Time;

                    (ix) comply with all applicable rules and regulations of the
                Commission, and make generally available to its securityholders
                as soon as practicable but no later than eighteen months after
                the effective date of such Exchange Registration Statement, an
                earning statement of the Company and its subsidiaries complying
                with Section 11(a) of the Securities Act (including, at the
                option of the Company, Rule 158 thereunder).

                (d) In connection with the Company's obligations with respect to
        the Shelf Registration, if applicable, the Company shall, as soon as
        reasonably practicable (or as otherwise specified):

                    (i) prepare and file with the Commission, as soon as
                reasonably practicable but in any case within the time periods
                specified in Section 2(b), a Shelf Registration Statement on any
                form which may be utilized by the Company and which shall
                register all of the Transfer Restricted Securities for resale by
                the holders thereof in accordance with such method or methods of
                disposition as may be specified by such of the holders as, from
                time to time, may be Electing Holders and use its best efforts
                to cause such Shelf Registration Statement to become effective
                as soon as practicable but in any case within the time periods
                specified in Section 2(b);

                    (ii) not less than 30 calendar days prior to the Effective
                Time of the Shelf Registration Statement, mail the Notice and
                Questionnaire to the holders of Transfer Restricted Securities;
                no holder shall be entitled to be named as a selling
                securityholder in the Shelf Registration Statement as of the
                Effective Time, and no holder shall be entitled to use the
                prospectus forming a part thereof for resales of Transfer
                Restricted Securities at any time, unless such holder has
                returned a completed and signed Notice and Questionnaire to the
                Company by the deadline for response set forth therein;
                provided, however, holders of Transfer Restricted

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                Securities shall have at least 28 calendar days from the date on
                which the Notice and Questionnaire is first mailed to such
                holders to return a completed and signed Notice and
                Questionnaire to the Company;

                    (iii) after the Effective Time of the Shelf Registration
                Statement, upon the request of any holder of Transfer Restricted
                Securities that is not then an Electing Holder, promptly send a
                Notice and Questionnaire to such holder; provided that the
                Company shall not be required to take any action to name such
                holder as a selling securityholder in the Shelf Registration
                Statement or to enable such holder to use the prospectus forming
                a part thereof for resales of Transfer Restricted Securities
                until such holder has returned a completed and signed Notice and
                Questionnaire to the Company;

                    (iv) as soon as practicable prepare and file with the
                Commission such amendments and supplements to such Shelf
                Registration Statement and the prospectus included therein as
                may be necessary to effect and maintain the effectiveness of
                such Shelf Registration Statement for the period specified in
                Section 2(b) hereof and as may be required by the applicable
                rules and regulations of the Commission and the instructions
                applicable to the form of such Shelf Registration Statement, and
                furnish to the Electing Holders copies of any such supplement or
                amendment simultaneously with or prior to its being used or
                filed with the Commission;

                    (v) comply with the provisions of the Securities Act with
                respect to the disposition of all of the Transfer Restricted
                Securities covered by such Shelf Registration Statement in
                accordance with the intended methods of disposition by the
                Electing Holders provided for in such Shelf Registration
                Statement;

                    (vi) provide (A) the Electing Holders, (B) the underwriters
                (which term, for purposes of this Registration Rights Agreement,
                shall include a Person deemed to be an underwriter within the
                meaning of Section 2(a)(11) of the Securities Act), if any,
                thereof, (C) any sales or placement agent therefor, (D) counsel
                for any such underwriter or agent and (E) not more than one
                counsel for all the Electing Holders the opportunity to
                participate in the preparation of such Shelf Registration
                Statement, each prospectus included therein or filed with the
                Commission and each amendment or supplement thereto;

                    (vii) for a reasonable period prior to the filing of such
                Shelf Registration Statement, and throughout the period
                specified in Section 2(b), make available at reasonable times at
                the Company's principal place of business or such other
                reasonable place for inspection by the Persons referred to in
                Section 3(d)(vi) who shall certify to the Company that they have
                a current intention to sell the Transfer Restricted Securities
                pursuant to the Shelf Registration such financial and other
                information and books and records of the Company, and cause the
                officers,

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                employees, counsel and independent certified public accountants
                of the Company to respond to such inquiries, as shall be
                reasonably necessary, in the judgment of the respective counsel
                referred to in such Section, to conduct a reasonable
                investigation within the meaning of Section 11 of the Securities
                Act; provided, however, that each such party shall be required
                to maintain in confidence and not to disclose to any other
                Person any information or records reasonably designated by the
                Company as being confidential, until such time as (A) such
                information becomes a matter of public record (whether by virtue
                of its inclusion in such registration statement or otherwise),
                or (B) such Person shall be required so to disclose such
                information pursuant to a subpoena or order of any court or
                other governmental agency or body having jurisdiction over the
                matter (subject to the requirements of such order, and only
                after such Person shall have given the Company prompt prior
                written notice of such requirement), or (C) such information is
                required to be set forth in such Shelf Registration Statement or
                the prospectus included therein or in an amendment to such Shelf
                Registration Statement or an amendment or supplement to such
                prospectus in order that such Shelf Registration Statement,
                prospectus, amendment or supplement, as the case may be,
                complies with applicable requirements of the federal securities
                laws and the rules and regulations of the Commission and does
                not contain an untrue statement of a material fact or omit to
                state therein a material fact required to be stated therein or
                necessary to make the statements therein not misleading in light
                of the circumstances then existing;

                    (viii) promptly notify each of the Electing Holders, any
                sales or placement agent therefor and any underwriter thereof
                (which notification may be made through any managing underwriter
                that is a representative of such underwriter for such purpose)
                and confirm such advice in writing, (A) when such Shelf
                Registration Statement or the prospectus included therein or any
                prospectus amendment or supplement or post-effective amendment
                has been filed, and, with respect to such Shelf Registration
                Statement or any post-effective amendment, when the same has
                become effective, (B) of any comments by the Commission and by
                the blue sky or securities commissioner or regulator of any
                state with respect thereto or any request by the Commission for
                amendments or supplements to such Shelf Registration Statement
                or prospectus or for additional information, (C) of the issuance
                by the Commission of any stop order suspending the effectiveness
                of such Shelf Registration Statement or the initiation or
                threatening of any proceedings for that purpose, (D) if at any
                time the representations and warranties of the Company
                contemplated by Section 3(d)(xvii) or Section 5 cease to be true
                and correct in all material respects, (E) of the receipt by the
                Company of any notification with respect to the suspension of
                the qualification of the Transfer Restricted Securities for sale
                in any jurisdiction or the initiation or threatening of any
                proceeding for such purpose, or (F) if at any time when a
                prospectus is required to be delivered under the Securities Act,
                that such Shelf Registration Statement, prospectus, prospectus
                amendment or supplement or post-effective

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                amendment does not conform in all material respects to the
                applicable requirements of the Securities Act and the Trust
                Indenture Act and the rules and regulations of the Commission
                thereunder or contains an untrue statement of a material fact or
                omits to state any material fact required to be stated therein
                or necessary to make the statements therein not misleading in
                light of the circumstances then existing;

                    (ix) use its commercially reasonable efforts to obtain the
                withdrawal of any order suspending the effectiveness of such
                registration statement or any post-effective amendment thereto
                at the earliest practicable date;

                    (x) if requested by any managing underwriter or
                underwriters, any placement or sales agent or any Electing
                Holder, promptly incorporate in a prospectus supplement or
                post-effective amendment such information as is required by the
                applicable rules and regulations of the Commission and as such
                managing underwriter or underwriters, such agent or such
                Electing Holder specifies should be included therein relating to
                the terms of the sale of such Transfer Restricted Securities,
                including information with respect to the principal amount of
                Transfer Restricted Securities being sold by such Electing
                Holder or agent or to any underwriters, the name and description
                of such Electing Holder, agent or underwriter, the offering
                price of such Transfer Restricted Securities and any discount,
                commission or other compensation payable in respect thereof, the
                purchase price being paid therefor by such underwriters and with
                respect to any other terms of the offering of the Transfer
                Restricted Securities to be sold by such Electing Holder or
                agent or to such underwriters; and make all required filings of
                such prospectus supplement or post-effective amendment promptly
                after notification of the matters to be incorporated in such
                prospectus supplement or post-effective amendment;

                    (xi) furnish to each Electing Holder, each placement or
                sales agent, if any, therefor, each underwriter, if any, thereof
                and the respective counsel referred to in Section 3(d)(vi) an
                executed copy (or, in the case of an Electing Holder, a
                conformed copy) of such Shelf Registration Statement, each such
                amendment and supplement thereto (in each case including all
                exhibits thereto (in the case of an Electing Holder of Transfer
                Restricted Securities, upon request) and documents incorporated
                by reference therein) and such number of copies of such Shelf
                Registration Statement (excluding exhibits thereto and documents
                incorporated by reference therein unless specifically so
                requested by such Electing Holder, agent or underwriter, as the
                case may be) and of the prospectus included in such Shelf
                Registration Statement (including each preliminary prospectus
                and any summary prospectus), in conformity in all material
                respects with the applicable requirements of the Securities Act
                and the Trust Indenture Act and the rules and regulations of the
                Commission thereunder, and such other documents, as such
                Electing Holder, agent, if any, and underwriter, if any, may
                reasonably request in

                                       12

<PAGE>   13
                order to facilitate the offering and disposition of the Transfer
                Restricted Securities owned by such Electing Holder, offered or
                sold by such agent or underwritten by such underwriter and to
                permit such Electing Holder, agent and underwriter to satisfy
                the prospectus delivery requirements of the Securities Act; and
                the Company hereby consents to the use of such prospectus
                (including such preliminary and summary prospectus) and any
                amendment or supplement thereto by each such Electing Holder and
                by any such agent and underwriter, in each case in the form most
                recently provided to such Person by the Company, in connection
                with the offering and sale of the Transfer Restricted Securities
                covered by the prospectus (including such preliminary and
                summary prospectus) or any supplement or amendment thereto;

                    (xii) use its commercially reasonable efforts to (A)
                register or qualify the Transfer Restricted Securities to be
                included in such Shelf Registration Statement under such
                securities laws or blue sky laws of such jurisdictions as any
                Electing Holder and each placement or sales agent, if any,
                therefor and underwriter, if any, thereof shall reasonably
                request, (B) keep such registrations or qualifications in effect
                and comply with such laws so as to permit the continuance of
                offers, sales and dealings therein in such jurisdictions during
                the period the Shelf Registration is required to remain
                effective under Section 2(b) above and for so long as may be
                necessary to enable any such Electing Holder, agent or
                underwriter to complete its distribution of Securities pursuant
                to such Shelf Registration Statement and (C) take any and all
                other actions as may be reasonably necessary or advisable to
                enable each such Electing Holder, agent, if any, and
                underwriter, if any, to consummate the disposition in such
                jurisdictions of such Transfer Restricted Securities; provided,
                however, that the Company shall not be required for any such
                purpose to (1) qualify as a foreign corporation in any
                jurisdiction wherein it would not otherwise be required to
                qualify but for the requirements of this Section 3(d)(xii), (2)
                consent to general service of process in any such jurisdiction
                or (3) make any changes to its certificate of incorporation or
                by-laws or any agreement between it and its stockholders;

                    (xiii) use its commercially reasonable efforts to obtain the
                consent or approval of each governmental agency or authority,
                whether federal, state or local, which may be required to effect
                the Shelf Registration or the offering or sale in connection
                therewith or to enable the selling holder or holders to offer,
                or to consummate the disposition of, their Transfer Restricted
                Securities;

                    (xiv) Unless any Transfer Restricted Securities shall be in
                book-entry only form, cooperate with the Electing Holders and
                the managing underwriters, if any, to facilitate the timely
                preparation and delivery of certificates representing Transfer
                Restricted Securities to be sold, which certificates, if so
                required by any securities exchange upon which any Transfer
                Restricted Securities are listed, shall be penned, lithographed
                or engraved, or produced by any combination of such

                                       13

<PAGE>   14
                methods, on steel engraved borders, and which certificates shall
                not bear any restrictive legends; and, in the case of an
                underwritten offering, enable such Transfer Restricted
                Securities to be in such denominations and registered in such
                names as the managing underwriters may request at least two
                business days prior to any sale of the Transfer Restricted
                Securities;

                    (xv) provide a CUSIP number for all Transfer Restricted
                Securities, not later than the applicable Effective Time;

                    (xvi) enter into one or more underwriting agreements,
                engagement letters, agency agreements, "best efforts"
                underwriting agreements or similar agreements, as appropriate,
                including customary provisions relating to indemnification and
                contribution, and take such other actions in connection
                therewith as any Electing Holders aggregating at least 20% in
                aggregate principal amount of the Transfer Restricted Securities
                at the time outstanding shall request in order to expedite or
                facilitate the disposition of such Transfer Restricted
                Securities;

                    (xvii) whether or not an agreement of the type referred to
                in Section 3(d)(xvi) hereof is entered into and whether or not
                any portion of the offering contemplated by the Shelf
                Registration is an underwritten offering or is made through a
                placement or sales agent or any other entity, (A) make such
                representations and warranties to the Electing Holders and the
                placement or sales agent, if any, therefor and the underwriters,
                if any, thereof in form, substance and scope as are customarily
                made in connection with an offering of debt securities pursuant
                to any appropriate agreement or to a registration statement
                filed on the form applicable to the Shelf Registration; (B)
                obtain an opinion of counsel to the Company in customary form
                and covering such matters, of the type customarily covered by
                such an opinion, as the managing underwriters, if any, or as any
                Electing Holders of at least 20% in aggregate principal amount
                of the Transfer Restricted Securities at the time outstanding
                may reasonably request, addressed to such Electing Holder or
                Electing Holders and the placement or sales agent, if any,
                therefor and the underwriters, if any, thereof and dated the
                effective date of such Shelf Registration Statement (and if such
                Shelf Registration Statement contemplates an underwritten
                offering of a part or all of the Transfer Restricted Securities,
                dated the date of the closing under the underwriting agreement
                relating thereto) (it being agreed that the matters to be
                covered by such opinion shall include the due incorporation and
                good standing of the Company and its subsidiaries; the
                qualification of the Company and its subsidiaries to transact
                business as foreign corporations; the due authorization,
                execution and delivery of the relevant agreement of the type
                referred to in Section 3(d)(xvi) hereof; the due authorization,
                execution, authentication and issuance, and the validity and
                enforceability, of the Securities; the absence of material legal
                or governmental

                                       14

<PAGE>   15
                proceedings involving the Company; the absence of a breach by
                the Company or any of its subsidiaries of, or a default under,
                material agreements binding upon the Company or any subsidiary
                of the Company; the absence of governmental approvals required
                to be obtained in connection with the Shelf Registration, the
                offering and sale of the Transfer Restricted Securities, this
                Registration Rights Agreement or any agreement of the type
                referred to in Section 3(d)(xvi) hereof, except such approvals
                as may be required under state securities or blue sky laws; the
                material compliance as to form of such Shelf Registration
                Statement and any documents incorporated by reference therein
                and of the Indenture with the requirements of the Securities Act
                and the Trust Indenture Act and the rules and regulations of the
                Commission thereunder, respectively; and, as of the date of the
                opinion and of the Shelf Registration Statement or most recent
                post-effective amendment thereto, as the case may be, the
                absence from such Shelf Registration Statement and the
                prospectus included therein, as then amended or supplemented,
                and from the documents incorporated by reference therein (in
                each case other than the financial statements and other
                financial information contained therein) of an untrue statement
                of a material fact or the omission to state therein a material
                fact necessary to make the statements therein not misleading (in
                the case of such documents, in the light of the circumstances
                existing at the time that such documents were filed with the
                Commission under the Exchange Act)); (C) obtain a "cold comfort"
                letter or letters from the independent certified public
                accountants of the Company addressed to the selling Electing
                Holders, the placement or sales agent, if any, therefor or the
                underwriters, if any, thereof, dated (i) the effective date of
                such Shelf Registration Statement and (ii) the effective date of
                any prospectus supplement to the prospectus included in such
                Shelf Registration Statement or post-effective amendment to such
                Shelf Registration Statement which includes unaudited or audited
                financial statements as of a date or for a period subsequent to
                that of the latest such statements included in such prospectus
                (and, if such Shelf Registration Statement contemplates an
                underwritten offering pursuant to any prospectus supplement to
                the prospectus included in such Shelf Registration Statement or
                post-effective amendment to such Shelf Registration Statement
                which includes unaudited or audited financial statements as of a
                date or for a period subsequent to that of the latest such
                statements included in such prospectus, dated the date of the
                closing under the underwriting agreement relating thereto), such
                letter or letters to be in customary form and covering such
                matters of the type customarily covered by letters of such type;
                (D) deliver such documents and certificates, including officers'
                certificates, as may be reasonably requested by any Electing
                Holders of at least 20% in aggregate principal amount of the
                Transfer Restricted Securities at the time outstanding or the
                placement or sales agent, if any, therefor and the managing
                underwriters, if any, thereof to evidence the accuracy of the
                representations and warranties made pursuant to clause (A) above
                or those contained in Section 5(a) hereof and the compliance
                with or satisfaction of any agreements or conditions contained
                in the underwriting agreement or other agreement entered into by
                the Company; and (E) undertake

                                       15

<PAGE>   16
                such obligations relating to expense reimbursement,
                indemnification and contribution as are provided in Section 6
                hereof;

                    (xviii)notify in writing each holder of Transfer Restricted
                Securities of any proposal by the Company to amend or waive any
                provision of this Registration Rights Agreement pursuant to
                Section 9(h) hereof and of any amendment or waiver effected
                pursuant thereto, each of which notices shall contain the text
                of the amendment or waiver proposed or effected, as the case may
                be;

                    (xix) in the event that any broker-dealer registered under
                the Exchange Act shall underwrite any Transfer Restricted
                Securities or participate as a member of an underwriting
                syndicate or selling group or "assist in the distribution"
                (within the meaning of the Conduct Rules (the "Conduct Rules) of
                the National Association of Securities Dealers, Inc. ("NASD") or
                any successor thereto, as amended from time to time) thereof,
                whether as a holder of such Transfer Restricted Securities or as
                an underwriter, a placement or sales agent or a broker or dealer
                in respect thereof, or otherwise, assist such broker-dealer in
                complying with the requirements of such Conduct Rules, including
                by (A) if such Conduct Rules shall so require, engaging a
                "qualified independent underwriter" (as defined in such Conduct
                Rules) to participate in the preparation of the Shelf
                Registration Statement relating to such Transfer Restricted
                Securities, to exercise usual standards of due diligence in
                respect thereto and, if any portion of the offering contemplated
                by such Shelf Registration Statement is an underwritten offering
                or is made through a placement or sales agent, to recommend the
                yield of such Transfer Restricted Securities, (B) indemnifying
                any such qualified independent underwriter to the extent of the
                indemnification of underwriters provided in Section 6 hereof (or
                to such other customary extent as may be requested by such
                underwriter), and (C) providing such information to such
                broker-dealer as may be required in order for such broker-dealer
                to comply with the requirements of the Conduct Rules; and

                    (xx) comply with all applicable rules and regulations of the
                Commission, and make generally available to its securityholders
                as soon as practicable but in any event not later than eighteen
                months after the effective date of such Shelf Registration
                Statement, an earning statement of the Company and its
                subsidiaries complying with Section 11(a) of the Securities Act
                (including, at the option of the Company, Rule 158 thereunder).

                (e) In the event that the Company would be required, pursuant to
        Section 3(d)(viii)(F) above, to notify the Electing Holders, the
        placement or sales agent, if any, therefor and the managing
        underwriters, if any, thereof, the Company shall without delay prepare
        and furnish to each of the Electing Holders, to each placement or sales
        agent, if any, and to each such underwriter, if any, a reasonable number
        of copies of a prospectus

                                       16

<PAGE>   17
        supplemented or amended so that, as thereafter delivered to purchasers
        of Transfer Restricted Securities, such prospectus shall conform in all
        material respects to the applicable requirements of the Securities Act
        and the Trust Indenture Act and the rules and regulations of the
        Commission thereunder and shall not contain an untrue statement of a
        material fact or omit to state a material fact required to be stated
        therein or necessary to make the statements therein not misleading in
        light of the circumstances then existing. Each Electing Holder agrees
        that upon receipt of any notice from the Company pursuant to Section
        3(d)(viii)(F) hereof, such Electing Holder shall forthwith discontinue
        the disposition of Transfer Restricted Securities pursuant to the Shelf
        Registration Statement applicable to such Transfer Restricted Securities
        until such Electing Holder shall have received copies of such amended or
        supplemented prospectus, and if so directed by the Company, such
        Electing Holder shall deliver to the Company (at the Company's expense)
        all copies, other than permanent file copies, then in such Electing
        Holder's possession of the prospectus covering such Transfer Restricted
        Securities at the time of receipt of such notice.

                (f) In the event of a Shelf Registration, in addition to the
        information required to be provided by each Electing Holder in its
        Notice Questionnaire, the Company may require such Electing Holder to
        furnish to the Company such additional information regarding such
        Electing Holder and such Electing Holder's intended method of
        distribution of Transfer Restricted Securities as may be required in
        order to comply with the Securities Act. Each such Electing Holder
        agrees to notify the Company as promptly as practicable of any
        inaccuracy or change in information previously furnished by such
        Electing Holder to the Company or of the occurrence of any event in
        either case as a result of which any prospectus relating to such Shelf
        Registration contains or would contain an untrue statement of a material
        fact regarding such Electing Holder or such Electing Holder's intended
        method of disposition of such Transfer Restricted Securities or omits to
        state any material fact regarding such Electing Holder or such Electing
        Holder's intended method of disposition of such Transfer Restricted
        Securities required to be stated therein or necessary to make the
        statements therein not misleading in light of the circumstances then
        existing, and promptly to furnish to the Company any additional
        information required to correct and update any previously furnished
        information or required so that such prospectus shall not contain, with
        respect to such Electing Holder or the disposition of such Transfer
        Restricted Securities, an untrue statement of a material fact or omit to
        state a material fact required to be stated therein or necessary to make
        the statements therein not misleading in light of the circumstances then
        existing.

                (g) Until the expiration of two years after the Closing Date,
        the Company will not, and will not permit any of its "affiliates" (as
        defined in Rule 144) it controls to, resell any of the Securities that
        have been reacquired by any of them except pursuant to an effective
        registration statement under the Securities Act.

               4. Registration Expenses. The Company agrees to bear and to pay
or cause to be paid promptly all expenses incident to the Company's performance
of or compliance with

                                       17

<PAGE>   18
this Registration Rights Agreement, including (a) all Commission and any NASD
registration, filing and review fees and expenses including fees and
disbursements of counsel for the placement or sales agent or underwriters in
connection with such registration, filing and review, (b) all fees and expenses
in connection with the qualification of the Securities for offering and sale
under the State securities and blue sky laws referred to in Section 3(d)(xii)
hereof and determination of their eligibility for investment under the laws of
such jurisdictions as any managing underwriters or the Electing Holders may
designate, including any fees and disbursements of counsel for the Electing
Holders or underwriters in connection with such qualification and determination,
(c) all expenses relating to the preparation, printing, production, distribution
and reproduction of each registration statement required to be filed hereunder,
each prospectus included therein or prepared for distribution pursuant hereto,
each amendment or supplement to the foregoing, the expenses of preparing the
Securities for delivery and the expenses of printing or producing any
underwriting agreements, agreements among underwriters, selling agreements and
blue sky or legal investment memoranda and all other documents in connection
with the offering, sale or delivery of Securities to be disposed of (including
certificates representing the Securities), (d) messenger, telephone and delivery
expenses relating to the offering, sale or delivery of Securities and the
preparation of documents referred in clause (c) above, (e) fees and expenses of
the Trustee under the Indenture, any agent of the Trustee and any counsel for
the Trustee and of any collateral agent or custodian, (f) internal expenses
(including all salaries and expenses of the Company's officers and employees
performing legal or accounting duties), (g) fees, disbursements and expenses of
counsel and independent certified public accountants of the Company (including
the expenses of any opinions or "cold comfort" letters required by or incident
to such performance and compliance), (h) reasonable fees, disbursements and
expenses of one counsel for the Electing Holders retained in connection with a
Shelf Registration, as selected by the Electing Holders of at least a majority
in aggregate principal amount of the Transfer Restricted Securities held by
Electing Holders (which counsel shall be reasonably satisfactory to the
Company), (i) any fees charged by securities rating services for rating the
Securities, and (j) fees, expenses and disbursements of any other Persons,
including special experts, retained by the Company in connection with such
registration (collectively, the "Registration Expenses"). To the extent that any
Registration Expenses are incurred, assumed or paid by any holder of Transfer
Restricted Securities or any placement or sales agent therefor or underwriter
thereof, the Company shall reimburse such Person for the full amount of the
Registration Expenses so incurred, assumed or paid promptly after receipt of a
request therefor. Notwithstanding the foregoing, the holders of the Transfer
Restricted Securities being registered shall pay all agency fees and commissions
and underwriting discounts and commissions attributable to the sale of such
Transfer Restricted Securities and the fees and disbursements of any counsel or
other advisors or experts retained by such holders (severally or jointly), other
than the counsel and experts specifically referred to above.

               5. Representations and Warranties. The Company represents and
warrants to, and agrees with, each Purchaser and each of the holders from time
to time of Transfer Restricted Securities that:

                                       18

<PAGE>   19
                (a) Each registration statement covering Transfer Restricted
        Securities and each prospectus (including any preliminary or summary
        prospectus) contained therein or furnished pursuant to Section 3(d) or
        Section 3(c) hereof and any further amendments or supplements to any
        such registration statement or prospectus, when it becomes effective or
        is filed with the Commission, as the case may be, and, in the case of an
        underwritten offering of Transfer Restricted Securities, at the time of
        the closing under the underwriting agreement relating thereto, will
        conform in all material respects to the requirements of the Securities
        Act and the Trust Indenture Act and the rules and regulations of the
        Commission thereunder and will not contain an untrue statement of a
        material fact or omit to state a material fact required to be stated
        therein or necessary to make the statements therein not misleading; and
        at all times subsequent to the Effective Time when a prospectus would be
        required to be delivered under the Securities Act, other than from (i)
        such time as a notice has been given to holders of Transfer Restricted
        Securities pursuant to Section 3(d)(viii)(F) or Section 3(c)(iii)(F)
        hereof until (ii) such time as the Company furnishes an amended or
        supplemented prospectus pursuant to Section 3(e) or Section 3(c)(iv)
        hereof, each such registration statement, and each prospectus (including
        any summary prospectus) contained therein or furnished pursuant to
        Section 3(d) or Section 3(c) hereof, as then amended or supplemented,
        will conform in all material respects to the requirements of the
        Securities Act and the Trust Indenture Act and the rules and regulations
        of the Commission thereunder and will not contain an untrue statement of
        a material fact or omit to state a material fact required to be stated
        therein or necessary to make the statements therein not misleading in
        the light of the circumstances then existing; provided, however, that
        this representation and warranty shall not apply to any statements or
        omissions made in reliance upon and in conformity with information
        furnished in writing to the Company by a holder of Transfer Restricted
        Securities expressly for use therein.

                (b) Any documents incorporated by reference in any prospectus
        referred to in Section 5(a) hereof, when they become or became effective
        or are or were filed with the Commission, as the case may be, will
        conform or conformed in all material respects to the requirements of the
        Securities Act or the Exchange Act, as applicable, and none of such
        documents will contain or contained an untrue statement of a material
        fact or will omit or omitted to state a material fact required to be
        stated therein or necessary to make the statements therein not
        misleading; provided, however, that this representation and warranty
        shall not apply to any statements or omissions made in reliance upon and
        in conformity with information furnished in writing to the Company by a
        holder of Transfer Restricted Securities expressly for use therein.

                (c) The compliance by the Company with all of the provisions of
        this Registration Rights Agreement and the consummation of the
        transactions herein contemplated will not conflict with or result in a
        breach of any of the terms or provisions of, or constitute a default
        under, any material indenture, mortgage, deed of trust, loan agreement
        or other agreement or instrument to which the Company or any subsidiary
        of the Company is a party or by which the Company or any subsidiary of
        the Company is

                                       19

<PAGE>   20
        bound or to which any of the property or assets of the Company or any
        subsidiary of the Company is subject, nor will such action result in any
        violation of the provisions of the certificate of incorporation, as
        amended, or the by-laws of the Company or any statute or any order, rule
        or regulation of any court or governmental agency or body having
        jurisdiction over the Company or any subsidiary of the Company or any of
        their properties; and no consent, approval, authorization, order,
        registration or qualification of or with any such court or governmental
        agency or body is required for the consummation by the Company of the
        transactions contemplated by this Registration Rights Agreement, except
        the registration under the Securities Act of the Securities,
        qualification of the Indenture under the Trust Indenture Act and such
        consents, approvals, authorizations, registrations or qualifications as
        may be required under State securities or blue sky laws in connection
        with the offering and distribution of the Securities.

                (d) This Registration Rights Agreement has been duly authorized,
        executed and delivered by the Company.

               6. Indemnification.

               (a) Indemnification by the Company. The Company will indemnify
and hold harmless each of the holders of Transfer Restricted Securities included
in an Exchange Registration Statement, each of the Electing Holders of Transfer
Restricted Securities included in a Shelf Registration Statement and each Person
who participates as a placement or sales agent or as an underwriter in any
offering or sale of such Transfer Restricted Securities against any losses,
claims, damages or liabilities, joint or several, to which such holder, agent or
underwriter may become subject under the Securities Act or otherwise, insofar as
such losses, claims, damages or liabilities (or actions in respect thereof)
arise out of or are based upon an untrue statement or alleged untrue statement
of a material fact contained in any Exchange Registration Statement or Shelf
Registration Statement, as the case may be, under which such Transfer Restricted
Securities were registered under the Securities Act, or any preliminary, final
or summary prospectus contained therein or furnished by the Company to any such
holder, Electing Holder, agent or underwriter, or any amendment or supplement
thereto, or arise out of or are based upon the omission or alleged omission to
state therein a material fact required to be stated therein or necessary to make
the statements therein not misleading, and will reimburse such holder, such
Electing Holder, such agent and such underwriter for any legal or other expenses
reasonably incurred by them in connection with investigating or defending any
such action or claim as such expenses are incurred; provided, however, that the
Company shall not be liable to any such Person in any such case to the extent
that any such loss, claim, damage or liability arises out of or is based upon an
untrue statement or alleged untrue statement or omission or alleged omission
made in such registration statement, or preliminary, final or summary
prospectus, or amendment or supplement thereto, in reliance upon and in
conformity with written information furnished to the Company by such Person
expressly for use therein.

               (b) Indemnification by the Holders and any Agents and
Underwriters. The Company may require, as a condition to including any Transfer
Restricted Securities in any

                                       20

<PAGE>   21
registration statement filed pursuant to Section 2(b) hereof and to entering
into any underwriting agreement with respect thereto, that the Company shall
have received an undertaking reasonably satisfactory to it from the Electing
Holder of such Transfer Restricted Securities and from each underwriter named in
any such underwriting agreement, severally and not jointly, to (i) indemnify and
hold harmless the Company, and all other holders of Transfer Restricted
Securities, against any losses, claims, damages or liabilities to which the
Company or such other holders of Transfer Restricted Securities may become
subject, under the Securities Act or otherwise, insofar as such losses, claims,
damages or liabilities (or actions in respect thereof) arise out of or are based
upon an untrue statement or alleged untrue statement of a material fact
contained in such registration statement, or any preliminary, final or summary
prospectus contained therein or furnished by the Company to any such Electing
Holder, agent or underwriter, or any amendment or supplement thereto, or arise
out of or are based upon the omission or alleged omission to state therein a
material fact required to be stated therein or necessary to make the statements
therein not misleading, in each case to the extent, but only to the extent, that
such untrue statement or alleged untrue statement or omission or alleged
omission was made in reliance upon and in conformity with written information
furnished to the Company by such Electing Holder or underwriter expressly for
use therein, and (ii) reimburse the Company for any legal or other expenses
reasonably incurred by the Company in connection with investigating or defending
any such action or claim as such expenses are incurred; provided, however, that
no such Electing Holder shall be required to undertake liability to any Person
under this Section 6(b) for any amounts in excess of the dollar amount of the
proceeds to be received by such Electing Holder from the sale of such Electing
Holder's Transfer Restricted Securities pursuant to such registration.

               (c) Notices of Claims, Etc. Promptly after receipt by an
indemnified party under subsection (a) or (b) above of written notice of the
commencement of any action, such indemnified party shall, if a claim in respect
thereof is to be made against an indemnifying party pursuant to the
indemnification provisions of or contemplated by this Section 6, notify such
indemnifying party in writing of the commencement of such action; but the
omission so to notify the indemnifying party shall not relieve it from any
liability which it may have to any indemnified party otherwise than under the
indemnification provisions of or contemplated by Section 6(a) or 6(b) hereof. In
case any such action shall be brought against any indemnified party and it shall
notify an indemnifying party of the commencement thereof, such indemnifying
party shall be entitled to participate therein and, to the extent that it shall
wish, jointly with any other indemnifying party similarly notified, to assume
the defense thereof, with counsel reasonably satisfactory to such indemnified
party (who shall not, except with the consent of the indemnified party, be
counsel to the indemnifying party), and, after notice from the indemnifying
party to such indemnified party of its election so to assume the defense
thereof, such indemnifying party shall not be liable to such indemnified party
for any legal expenses of other counsel or any other expenses, in each case
subsequently incurred by such indemnified party, in connection with the defense
thereof other than reasonable costs of investigation. No indemnifying party
shall, without the written consent of the indemnified party, effect the
settlement or compromise of, or consent to the entry of any judgment with
respect to, any pending or threatened action or claim in respect of which
indemnification or contribution may be

                                       21

<PAGE>   22
sought hereunder (whether or not the indemnified party is an actual or potential
party to such action or claim) unless such settlement, compromise or judgment
(i) includes an unconditional release of the indemnified party from all
liability arising out of such action or claim and (ii) does not include a
statement as to or an admission of fault, culpability or a failure to act by or
on behalf of any indemnified party.

               (d) Contribution. If for any reason the indemnification
provisions contemplated by Section 6(a) or Section 6(b) are unavailable to or
insufficient to hold harmless an indemnified party in respect of any losses,
claims, damages or liabilities (or actions in respect thereof) referred to
therein, then each indemnifying party shall contribute to the amount paid or
payable by such indemnified party as a result of such losses, claims, damages or
liabilities (or actions in respect thereof) in such proportion as is appropriate
to reflect the relative fault of the indemnifying party and the indemnified
party in connection with the statements or omissions which resulted in such
losses, claims, damages or liabilities (or actions in respect thereof), as well
as any other relevant equitable considerations. The relative fault of such
indemnifying party and indemnified party shall be determined by reference to,
among other things, whether the untrue or alleged untrue statement of a material
fact or omission or alleged omission to state a material fact relates to
information supplied by such indemnifying party or by such indemnified party,
and the parties' relative intent, knowledge, access to information and
opportunity to correct or prevent such statement or omission. The parties hereto
agree that it would not be just and equitable if contributions pursuant to this
Section 6(d) were determined by pro rata allocation (even if the holders or any
agents or underwriters or all of them were treated as one entity for such
purpose) or by any other method of allocation which does not take account of the
equitable considerations referred to in this Section 6(d). The amount paid or
payable by an indemnified party as a result of the losses, claims, damages, or
liabilities (or actions in respect thereof) referred to above shall be deemed to
include any legal or other fees or expenses reasonably incurred by such
indemnified party in connection with investigating or defending any such action
or claim. Notwithstanding the provisions of this Section 6(d), no holder shall
be required to contribute any amount in excess of the amount by which the dollar
amount of the proceeds received by such holder from the sale of any Transfer
Restricted Securities (after deducting any fees, discounts and commissions
applicable thereto) exceeds the amount of any damages which such holder has
otherwise been required to pay by reason of such untrue or alleged untrue
statement or omission or alleged omission, and no underwriter shall be required
to contribute any amount in excess of the amount by which the total price at
which the Transfer Restricted Securities underwritten by it and distributed to
the public were offered to the public exceeds the amount of any damages which
such underwriter has otherwise been required to pay by reason of such untrue or
alleged untrue statement or omission or alleged omission. No Person guilty of
fraudulent misrepresentation (within the meaning of Section 11(f) of the
Securities Act) shall be entitled to contribution from any Person who was not
guilty of such fraudulent misrepresentation. The holders' and any underwriters'
obligations in this Section 6(d) to contribute shall be several in proportion to
the principal amount of Transfer Restricted Securities registered or
underwritten, as the case may be, by them and not joint.

                                       22

<PAGE>   23
               (e) The obligations of the Company under this Section 6 shall be
in addition to any liability which the Company may otherwise have and shall
extend, upon the same terms and conditions, to each officer, director and
partner of each holder, agent and underwriter and each Person, if any, who
controls any holder, agent or underwriter within the meaning of the Securities
Act; and the obligations of the holders and any agents or underwriters
contemplated by this Section 6 shall be in addition to any liability which the
respective holder, agent or underwriter may otherwise have and shall extend,
upon the same terms and conditions, to each officer and director of the Company
(including any Person who, with his consent, is named in any registration
statement as about to become a director of the Company) and to each Person, if
any, who controls the Company within the meaning of the Securities Act.

               7. Underwritten Offerings.

               (a) Selection of Underwriters. If any of the Transfer Restricted
Securities covered by the Shelf Registration are to be sold pursuant to an
underwritten offering, the managing underwriter or underwriters thereof shall be
designated by Electing Holders holding at least a majority in aggregate
principal amount of the Transfer Restricted Securities to be included in such
offering, provided that such designated managing underwriter or underwriters is
or are reasonably acceptable to the Company.

               (b) Participation by Holders. Each holder of Transfer Restricted
Securities hereby agrees with each other such holder that no such holder may
participate in any underwritten offering hereunder unless such holder (i) agrees
to sell such holder's Transfer Restricted Securities on the basis provided in
any underwriting arrangements approved by the Persons entitled hereunder to
approve such arrangements and (ii) completes and executes all questionnaires,
powers of attorney, indemnities, underwriting agreements and other documents
reasonably required under the terms of such underwriting arrangements.

               8. Rule 144. The Company covenants to the holders of Transfer
Restricted Securities that to the extent it shall be required to do so under the
Exchange Act, the Company shall timely file the reports required to be filed by
it under the Exchange Act or the Securities Act (including the reports under
Section 13 and 15(d) of the Exchange Act referred to in subparagraph (c)(1) of
Rule 144 adopted by the Commission under the Securities Act) and the rules and
regulations adopted by the Commission thereunder, and shall take such further
action as any holder of Transfer Restricted Securities may reasonably request,
all to the extent required from time to time to enable such holder to sell
Transfer Restricted Securities without registration under the Securities Act
within the limitations of the exemption provided by Rule 144 under the
Securities Act, as such Rule may be amended from time to time, or any similar or
successor rule or regulation hereafter adopted by the Commission. Upon the
request of any holder of Transfer Restricted Securities in connection with that
holder's sale pursuant to Rule 144, the Company shall deliver to such holder a
written statement as to whether it has complied with such requirements.

                                       23

<PAGE>   24
               9. Miscellaneous.

               (a) No Inconsistent Agreements. The Company represents, warrants,
covenants and agrees that it has not granted, and shall not grant, registration
rights with respect to Transfer Restricted Securities or any other securities
which would be inconsistent with the terms contained in this Registration Rights
Agreement.

               (b) Specific Performance. The parties hereto acknowledge that
there would be no adequate remedy at law if the Company fails to perform any of
its obligations hereunder and that the Purchasers and the holders from time to
time of the Transfer Restricted Securities may be irreparably harmed by any such
failure, and accordingly agree that the Purchasers and such holders, in addition
to any other remedy to which they may be entitled at law or in equity, shall be
entitled to compel specific performance of the obligations of the Company under
this Registration Rights Agreement in accordance with the terms and conditions
of this Registration Rights Agreement, in any court of the United States or any
State thereof having jurisdiction.

               (c) Notices. All notices, requests, claims, demands, waivers and
other communications hereunder shall be in writing and shall be deemed to have
been duly given when delivered by hand, if delivered personally or by courier,
or three days after being deposited in the mail (registered or certified mail,
postage prepaid, return receipt requested) as follows: If to the Company, to it
at COLO.COM, 2000 Sierra Point Parkway, Suite 601, Brisbane, California
94005-1819, Attention: David H. Stanley, and if to a holder, to the address of
such holder set forth in the security register or other records of the Company,
or to such other address as the Company or any such holder may have furnished to
the other in writing in accordance herewith, except that notices of change of
address shall be effective only upon receipt.

               (d) Parties in Interest. All the terms and provisions of this
Registration Rights Agreement shall be binding upon, shall inure to the benefit
of and shall be enforceable by the parties hereto and the holders from time to
time of the Transfer Restricted Securities and the respective successors and
assigns of the parties hereto and such holders. In the event that any transferee
of any holder of Transfer Restricted Securities shall acquire Transfer
Restricted Securities, in any manner, whether by gift, bequest, purchase,
operation of law or otherwise, such transferee shall, without any further
writing or action of any kind, be deemed a beneficiary hereof for all purposes
and such Transfer Restricted Securities shall be held subject to all of the
terms of this Registration Rights Agreement, and by taking and holding such
Transfer Restricted Securities such transferee shall be entitled to receive the
benefits of, and be conclusively deemed to have agreed to be bound by all of the
applicable terms and provisions of this Registration Rights Agreement. If the
Company shall so request, any such successor, assign or transferee shall agree
in writing to acquire and hold the Transfer Restricted Securities subject to all
of the applicable terms hereof.

               (e) Survival. The respective indemnities, agreements,
representations, warranties and each other provision set forth in this
Registration Rights Agreement or made pursuant hereto shall remain in full force
and effect regardless of any investigation (or statement

                                       24

<PAGE>   25
as to the results thereof) made by or on behalf of any holder of Transfer
Restricted Securities, any director, officer or partner of such holder, any
agent or underwriter or any director, officer or partner thereof, or any
controlling Person of any of the foregoing, and shall survive delivery of and
payment for the Transfer Restricted Securities pursuant to the Purchase
Agreement and the transfer and registration of Transfer Restricted Securities by
such holder and the consummation of an Exchange Offer.

               (f) GOVERNING LAW. THIS REGISTRATION RIGHTS AGREEMENT SHALL BE
GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK.

               (g) Headings. The descriptive headings of the several Sections
and paragraphs of this Registration Rights Agreement are inserted for
convenience only, do not constitute a part of this Registration Rights Agreement
and shall not affect in any way the meaning or interpretation of this
Registration Rights Agreement.

               (h) Entire Agreement; Amendments. This Registration Rights
Agreement and the other writings referred to herein (including the Indenture and
the form of Securities) or delivered pursuant hereto which form a part hereof
contain the entire understanding of the parties with respect to its subject
matter. This Registration Rights Agreement supersedes all prior agreements and
understandings between the parties with respect to its subject matter. This
Registration Rights Agreement may be amended and the observance of any term of
this Registration Rights Agreement may be waived (either generally or in a
particular instance and either retroactively or prospectively) only by a written
instrument duly executed by the Company and the holders of at least [a majority]
in aggregate principal amount of the Transfer Restricted Securities at the time
outstanding. Each holder of any Transfer Restricted Securities at the time or
thereafter outstanding shall be bound by any amendment or waiver effected
pursuant to this Section 9(h), whether or not any notice, writing or marking
indicating such amendment or waiver appears on such Transfer Restricted
Securities or is delivered to such holder.

               (i) Inspection. For so long as this Registration Rights Agreement
shall be in effect, this Registration Rights Agreement and a complete list of
the names and addresses of all the holders of Transfer Restricted Securities
shall be made available for inspection and copying on any business day by any
holder of Transfer Restricted Securities for proper purposes only (which shall
include any purpose related to the rights of the holders of Transfer Restricted
Securities under the Securities, the Indenture and this Agreement) at the
offices of the Company at the address thereof set forth in Section 9(c) above
and at the office of the Trustee under the Indenture.

               (j) Counterparts. This agreement may be executed by the parties
in counterparts, each of which shall be deemed to be an original, but all such
respective counterparts shall together constitute one and the same instrument.

                                       25

<PAGE>   26
               If the foregoing is in accordance with your understanding, please
sign and return to us nine counterparts hereof, and upon the acceptance hereof
by you, on behalf of each of the Purchasers, this letter and such acceptance
hereof shall constitute a binding agreement between each of the Purchasers and
the Company. It is understood that your acceptance of this letter on behalf of
each of the Purchasers is pursuant to the authority set forth in a form of
Agreement among Purchasers, the form of which shall be submitted to the Company
for examination upon request, but without warranty on your part as to the
authority of the signers thereof.

                                    Very truly yours,

                                        COLO.COM

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

Accepted as of the date hereof:
Goldman, Sachs & Co.
Bear, Stearns & Co. Inc.
Chase Securities Inc.
Deutsche Bank Securities Inc.
Warburg Dillon Read LLC
Jefferies & Company, Inc.

By: /s/ Goldman, Sachs & Co.
   -------------------------------
       (Goldman, Sachs & Co.)
On behalf of each of the Purchasers

                                       26

<PAGE>   27
                                                                       EXHIBIT A

                                    COLO.COM

                         INSTRUCTION TO DTC PARTICIPANTS

                                (DATE OF MAILING)

                     URGENT - IMMEDIATE ATTENTION REQUESTED

                         DEADLINE FOR RESPONSE: [DATE]*

               The Depository Trust Company ("DTC") has identified you as a DTC
Participant through which beneficial interests in the COLO.COM (the "Company")
13 7/8% Senior Notes due 2010 (the "Securities") are held.

               The Company is in the process of registering the Securities under
the Securities Act of 1933 for resale by the beneficial owners thereof. In order
to have their Securities included in the registration statement, beneficial
owners must complete and return the enclosed Notice of Registration Statement
and Selling Securityholder Questionnaire.

               It is important that beneficial owners of the Securities receive
a copy of the enclosed materials as soon as possible as their rights to have the
Securities included in the registration statement depend upon their returning
the Notice and Questionnaire by [Deadline For Response]. Please forward a copy
of the enclosed documents to each beneficial owner that holds interests in the
Securities through you. If you require more copies of the enclosed materials or
have any questions pertaining to this matter, please contact COLO.COM.

--------

* Not less than 28 calendar days from date of mailing.

<PAGE>   28
                                    COLO.COM

                        NOTICE OF REGISTRATION STATEMENT
                                       AND
                      SELLING SECURITYHOLDER QUESTIONNAIRE

                                     (DATE)

               Reference is hereby made to the Registration Rights Agreement
(the " Registration Rights Agreement") between COLO.COM (the "Company") and the
Purchasers named therein. Pursuant to the Registration Rights Agreement, the
Company has filed with the United States Securities and Exchange Commission (the
"Commission") a registration statement on Form [ ] (the "Shelf Registration
Statement") for the registration and resale under Rule 415 of the Securities Act
of 1933, as amended (the "Securities Act"), of the Company's 13 7/8% Senior
Notes due 2010 (the "Securities"). A copy of the Registration Rights Agreement
is attached hereto. All capitalized terms not otherwise defined herein shall
have the meanings ascribed thereto in the Registration Rights Agreement.

               Each beneficial owner of Transfer Restricted Securities (as
defined below) is entitled to have the Transfer Restricted Securities
beneficially owned by it included in the Shelf Registration Statement. In order
to have Transfer Restricted Securities included in the Shelf Registration
Statement, this Notice of Registration Statement and Selling Securityholder
Questionnaire ("Notice and Questionnaire") must be completed, executed and
delivered to the Company's counsel at the address set forth herein for receipt
ON OR BEFORE [Deadline for Response]. Beneficial owners of Transfer Restricted
Securities who do not complete, execute and return this Notice and Questionnaire
by such date (i) will not be named as selling securityholders in the Shelf
Registration Statement and (ii) may not use the Prospectus forming a part
thereof for resales of Transfer Restricted Securities.

               Certain legal consequences arise from being named as a selling
securityholder in the Shelf Registration Statement and related Prospectus.
Accordingly, holders and beneficial owners of Transfer Restricted Securities are
advised to consult their own securities law counsel regarding the consequences
of being named or not being named as a selling securityholder in the Shelf
Registration Statement and related Prospectus.

               The term "Transfer Restricted Securities" is defined in the
Registration Rights Agreement.

                                       2

<PAGE>   29
                                    ELECTION

               The undersigned holder (the "Selling Securityholder") of Transfer
Restricted Securities hereby elects to include in the Shelf Registration
Statement the Transfer Restricted Securities beneficially owned by it and listed
below in Item (3). The undersigned, by signing and returning this Notice and
Questionnaire, agrees to be bound with respect to such Transfer Restricted
Securities by the terms and conditions of this Notice and Questionnaire and the
Registration Rights Agreement, including, without limitation, Section 6 of the
Registration Rights Agreement, as if the undersigned Selling Securityholder were
an original party thereto.

               Upon any sale of Transfer Restricted Securities pursuant to the
Shelf Registration Statement, the Selling Securityholder will be required to
deliver to the Company and Trustee the Notice of Transfer set forth in Appendix
A to the Prospectus and as Exhibit B to the Registration Rights Agreement.

               The Selling Securityholder hereby provides the following
information to the Company and represents and warrants that such information is
accurate and complete:

                                       3

<PAGE>   30
                                  QUESTIONNAIRE

(1)(a)         Full Legal Name of Selling Securityholder:

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

(b)     Full Legal Name of Registered Holder (if not the same as in (a) above)
        of Transfer Restricted Securities Listed in Item (3) below:

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

(c)     Full Legal Name of DTC Participant (if applicable and if not the same as
        (b) above) Through Which Transfer Restricted Securities Listed in Item
        (3) below are Held:

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

(2)     Address for Notices to Selling Securityholder:

               Telephone:
                         ---------------------------------

               Fax:
                   ---------------------------------------

               Contact Person:
                              ----------------------------

(3)     Beneficial Ownership of Securities:

        Except as set forth below in this Item (3), the undersigned does not
        beneficially own any Securities.

        (a)     Principal amount of Transfer Restricted Securities beneficially
                owned:
                      ---------------------------------------------------------
                CUSIP No(s). of such Transfer Restricted Securities:
                                                                    -----------
        (b)     Principal amount of Securities other than Transfer Restricted
                Securities beneficially owned:

                ---------------------------------------------------------------
                CUSIP No(s). of such other Securities:

        (c)     Principal amount of Transfer Restricted Securities which the
                undersigned wishes to be included in the Shelf Registration
                Statement:
                          -----------------------------------------------------

                CUSIP No(s). of such Transfer Restricted Securities to be
                included in the Shelf Registration Statement:
                                                             ------------------

(4)     Beneficial Ownership of Other Securities of the Company:

                                       1

<PAGE>   31
        Except as set forth below in this Item (4), the undersigned Selling
        Securityholder is not the beneficial or registered owner of any other
        securities of the Company, other than the Securities listed above in
        Item (3).

        State any exceptions here:

(5)     Relationships with the Company:

        Except as set forth below, neither the Selling Securityholder nor any of
        its affiliates, officers, directors or principal equity holders (5% or
        more) has held any position or office or has had any other material
        relationship with the Company (or its predecessors or affiliates) during
        the past three years.

        State any exceptions here:

(6)     Plan of Distribution:

        Except as set forth below, the undersigned Selling Securityholder
        intends to distribute the Transfer Restricted Securities listed above in
        Item (3) only as follows (if at all): Such Transfer Restricted
        Securities may be sold from time to time directly by the undersigned
        Selling Securityholder or, alternatively, through underwriters,
        broker-dealers or agents. Such Transfer Restricted Securities may be
        sold in one or more transactions at fixed prices, at prevailing market
        prices at the time of sale, at varying prices determined at the time of
        sale, or at negotiated prices. Such sales may be effected in
        transactions (which may involve crosses or block transactions) (i) on
        any national securities exchange or quotation service on which the
        Registered Securities may be listed or quoted at the time of sale, (ii)
        in the over-the-counter market, (iii) in transactions otherwise than on
        such exchanges or services or in the over-the-counter market, or (iv)
        through the writing of options. In connection with sales of the Transfer
        Restricted Securities or otherwise, the Selling Securityholder may enter
        into hedging transactions with broker-dealers, which may in turn engage
        in short sales of the Transfer Restricted Securities in the course of
        hedging the positions they assume. The Selling Securityholder may also
        sell Transfer Restricted Securities short and deliver Transfer
        Restricted Securities to close out such short positions, or loan or
        pledge Transfer Restricted Securities to broker-dealers that in turn may
        sell such securities.

        State any exceptions here:

                                       2

<PAGE>   32
By signing below, the Selling Securityholder acknowledges that it understands
its obligation to comply, and agrees that it will comply, with the provisions of
the Exchange Act and the rules and regulations thereunder, particularly
Regulation M.

In the event that the Selling Securityholder transfers all or any portion of the
Transfer Restricted Securities listed in Item (3) above after the date on which
such information is provided to the Company, the Selling Securityholder agrees
to notify the transferee(s) at the time of the transfer of its rights and
obligations under this Notice and Questionnaire and the Registration Rights
Agreement.

By signing below, the Selling Securityholder consents to the disclosure of the
information contained herein in its answers to Items (1) through (6) above and
the inclusion of such information in the Shelf Registration Statement and
related Prospectus. The Selling Securityholder understands that such information
will be relied upon by the Company in connection with the preparation of the
Shelf Registration Statement and related Prospectus.

In accordance with the Selling Securityholder's obligation under Section 3(d) of
the Registration Rights Agreement to provide such information as may be required
by law for inclusion in the Shelf Registration Statement, the Selling
Securityholder agrees to promptly notify the Company of any inaccuracies or
changes in the information provided herein which may occur subsequent to the
date hereof at any time while the Shelf Registration Statement remains in
effect. All notices hereunder and pursuant to the Registration Rights Agreement
shall be made in writing, by hand-delivery, first-class mail, or air courier
guaranteeing overnight delivery as follows:

           (i)    To the Company:

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

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

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

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

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

           (ii) With a copy to:

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

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

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

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

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

Once this Notice and Questionnaire is executed by the Selling Securityholder and
received by the Company's counsel, the terms of this Notice and Questionnaire,
and the representations and warranties contained herein, shall be binding on,
shall inure to the benefit of and shall be enforceable by the respective
successors, heirs, personal representatives, and assigns of the Company and the
Selling Securityholder (with respect to the Transfer Restricted Securities

                                       3

<PAGE>   33
beneficially owned by such Selling Securityholder and listed in Item (3) above.
This Agreement shall be governed in all respects by the laws of the State of New
York.

                                       4

<PAGE>   34
IN WITNESS WHEREOF, the undersigned, by authority duly given, has caused this
Notice and Questionnaire to be executed and delivered either in person or by its
duly authorized agent.

Dated:
      -------------------------------

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

        Selling Securityholder
        (Print/type full legal name of beneficial owner of Transfer Restricted
        Securities)

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

PLEASE RETURN THE COMPLETED AND EXECUTED NOTICE AND QUESTIONNAIRE FOR RECEIPT ON
OR BEFORE [DEADLINE FOR RESPONSE] TO THE COMPANY'S COUNSEL AT:

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

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

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

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

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

                                       5

<PAGE>   35
                                                                       EXHIBIT B

              NOTICE OF TRANSFER PURSUANT TO REGISTRATION STATEMENT

State Street Bank and Trust
   Company of California, N.A.
COLO.COM
c/o State Street Bank and Trust
         Company
2 Avenue de Lafayette
Boston, MA 02111-1724

Attention: Sandy Wong
Telephone: (617) 662-1545
Fax:           (617) 662-1452

        Re:    COLO.COM (the "Company")
               13 7/8% Senior Notes due 2010

Dear Sirs:

               Please be advised that _____________________ has transferred
$____ aggregate principal amount of the above-referenced Notes pursuant to an
effective Registration Statement on Form [__] (File No. 333-_____) filed by the
Company.

               We hereby certify that the prospectus delivery requirements, if
any, of the Securities Act of 1933, as amended, have been satisfied and that the
above-named beneficial owner of the Notes is named as a "Selling Holder" in the
Prospectus dated ___________, ____ or in supplements thereto, and that the
aggregate principal amount of the Notes transferred are the Notes listed in such
Prospectus opposite such owner's name.

Dated:

                               Very truly yours,

                                             (Name)

                               By:
                                  ------------------------------------
                                      (Authorized Signature)<PAGE>   1
                                                                    EXHIBIT 10.1

                                    COLO.COM

                 AMENDED AND RESTATED INVESTORS RIGHTS AGREEMENT

        This Amended and Restated Investors Rights Agreement is made as of
December 17, 1999 by and among COLO.COM, a California corporation located at
2000 Sierra Point Parkway, Suite 600, Brisbane, California 94005 (the
"Company"), and the Holders (as defined below) listed on Exhibit A attached
hereto. This Amended and Restated Investors Rights Agreement supersedes and
replaces, in its entirety, the Amended and Restated Investors Rights Agreement
dated April 27, 1999 entered into among the Company and certain of the Holders
(the "Prior Rights Agreement").

        1. Registration Rights. The Company covenants and agrees as follows:

               1.1 Definitions. For purposes of this Section 1:

                      (a) The term "register," "registered," and "registration"
refer to a registration effected by preparing and filing a registration
statement or similar document in compliance with the Securities Act of 1933, as
amended (the "Act"), and the declaration or ordering of effectiveness of such
registration statement or document;

                      (b) The term "Registrable Securities" means the Common
Stock, (i) issuable or issued upon conversion of the Series C Preferred Stock
issued pursuant to the Series C Preferred Stock Purchase Agreement of even date
herewith (the "Series C Agreement"), (ii) issuable or issued upon the conversion
of the Series B Preferred Stock issued pursuant to the Series B Preferred Stock
Purchase Agreement dated April 27, 1999 (the "Series B Agreement"), (iii)
issuable or issued upon conversion of the Series A Preferred Stock and (iv) any
Common Stock of the Company issued as (or issuable upon the conversion or
exercise of any warrant, right or other security that is issued as) a dividend
or other distribution with respect to, or in exchange for or in replacement of,
such Common Stock referred to in (i), (ii), and (iii) above, excluding in all
cases, however, (i) any Registrable Securities sold by a person in a transaction
in which such person's rights under this Section 1 are not assigned, or (ii) any
Registrable Securities sold to or through a broker or dealer or underwriter in a
public distribution or a public securities transaction;

                      (c) The number of shares of "Registrable Securities then
outstanding" shall be determined by the number of shares of Common Stock
outstanding that are, and the number of shares of Common Stock issuable pursuant
to then exercisable or convertible securities that are, Registrable Securities;

                      (d) The term "Holder" means any person owning or having
the right to acquire Registrable Securities or any assignee thereof in
accordance with Section 1.13 hereof;

                      (e) The term "Form S-3" means such form under the Act as
in effect on the date hereof or any registration form under the Act subsequently
adopted by the Securities and

<PAGE>   2

Exchange Commission (the "SEC") that permits inclusion or incorporation of
substantial information by reference to other documents filed by the Company
with the SEC; and

                      (f) The term "Investor" means each Investor named in the
Series B Agreement or named in the Series C Agreement.

               1.2    Request for Registration.

                      (a) If the Company shall receive a written request from
the Holders of more than 50% of the Registrable Securities (the "Initiating
Holders") that the Company file a registration statement under the Act covering
the registration of at least 40% of all Registrable Securities (or a lesser
amount provided that the aggregate offering price, net of underwriting discounts
and commissions, is expected to exceed $10,000,000) then the Company shall,
within ten days of the receipt thereof, give written notice of such request to
all Holders and shall, subject to the limitations of Section 1.2(b), use its
best efforts to effect as soon as practicable the registration under the Act of
all Registrable Securities that the Holders request to be registered within 20
days of the mailing of such written notice by the Company; provided, however,
that the Company shall not be obligated to take any action to effect any such
registration, qualification or compliance pursuant to this Section 1.2(a):

                                 (i) During the period starting with the date 90
days prior to the Company's estimated date of filing of, and ending on the date
180 days immediately following the effective date of, any registration statement
pertaining to securities of the Company (other than a registration of securities
in a Rule 145 transaction or with respect to an employee benefit plan), provided
that the Company is actively employing in good faith all reasonable efforts to
cause such registration statement to become effective;

                                 (ii) During the period starting with the
effective date of the first registration statement for a public offering of
securities of the Company (other than a registration statement relating either
to the sale of securities to employees of the Company pursuant to a stock
option, stock purchase or similar plan or a SEC Rule 145 transaction) (the
"Initial Registration"), and ending on the date 180 days immediately following
the effective date of such registration statement;

                                 (iii) After the Company has effected two such
registrations pursuant to this Section 1.2(a), and such registrations have been
declared or ordered effective;

                                 (iv) If the Company shall furnish to such
Holders a certificate signed by the President of the Company stating that in the
good faith judgment of the Board of Directors it would be seriously detrimental
to the Company or its shareholders for a registration statement to be filed at
such time, then the Company's obligation to use its best efforts to register,
qualify or comply under this Section 1.2(a) shall be deferred for a period not
to exceed 120 days from the date of receipt of written request from the Holders;
provided, however, that the Company may not utilize this right more than once in
any twelve-month period; or

                                      -2-
<PAGE>   3

                                 (v) Prior to December 31, 2000.

                      (b) If the Holders initiating the registration request
hereunder (the "Initiating Holders") intend to distribute the Registrable
Securities covered by their request by means of an underwriting, they shall so
advise the Company as a part of their request made pursuant to this Section 1.2
and the Company shall include such information in the written notice referred to
in Section 1.2(a). In such event, the right of any Holder to include such
Holder's Registrable Securities in such registration shall be conditioned upon
such Holder's participation in such underwriting and the inclusion of such
Holder's Registrable Securities in the underwriting (unless otherwise mutually
agreed by a majority in interest of the Initiating Holders and such Holder) to
the extent provided herein. All Holders proposing to distribute their securities
through such underwriting shall (together with the Company as provided in
Section 1.4(e)) enter into an underwriting agreement in customary form with the
underwriter or underwriters selected for such underwriting by a majority in
interest of the Initiating Holders. Notwithstanding any other provision of this
Section 1.2, if the underwriter advises the Initiating Holders in writing that
marketing factors require a limitation of the number of shares to be
underwritten, then the Initiating Holders shall so advise all Holders of
Registrable Securities that would otherwise be underwritten pursuant hereto, and
the number of shares of Registrable Securities that may be included in the
underwriting shall be allocated first among the Initiating Holders and, after
all Registrable Securities owned by the Initiating Holders and included in the
request for registration pursuant to Section 1.2 have been included, then among
all other Holders of Registrable Securities, in proportion (as nearly as
practicable) to the amount of Registrable Securities of the Company owned by
each Holder participating in such underwriting; provided, however, that the
number of shares of Registrable Securities to be included in such underwriting
and registration shall not be reduced unless all other securities of the Company
are first entirely excluded from the underwriting and registration.

               1.3 Company Registration. If (but without any obligation to do
so) the Company proposes to register (including for this purpose a registration
effected by the Company for shareholders other than the Holders) any of its
stock or other securities under the Act in connection with the public offering
of such securities solely for cash (other than a registration relating solely to
the sale of securities to participants in a Company stock plan, or a
registration on any form that does not include substantially the same
information as would be required to be included in a registration statement
covering the sale of the Registrable Securities), the Company shall, at such
time, promptly give each Holder written notice of such registration. Upon the
written request of each Holder given within 20 days after mailing of written
notice by the Company, the Company shall, subject to the provisions of Section
1.8, cause to be registered under the Act all of the Registrable Securities
Shares that each such Holder has requested to be registered. After the date of
this Agreement, no shareholder or prospective shareholder of the Company shall
be granted piggyback registration rights that would reduce the number of shares
of Registrable Securities includable by a Holder in a registration under this
Section 1.3 without the written consent of Holders of at least two-thirds of the
Registrable Securities.

                                      -3-
<PAGE>   4

               1.4 Obligations of the Company. Whenever required under this
Section 1 to effect the registration of any Registrable Securities, the Company
shall, as expeditiously as reasonably possible:

                      (a) Prepare and file with the SEC a registration statement
with respect to such Registrable Securities and use its best efforts to cause
such registration statement to become effective, and, upon the request of the
holders of a majority of the Registrable Securities registered thereunder, keep
such registration statement effective for the earlier of 90 days or until the
distribution described in the Registration Statement has been completed.

                      (b) Prepare and file with the SEC such amendments and
supplements to such registration statement and the prospectus used in connection
with such registration statement as may be necessary to comply with the
provisions of the Act with respect to the disposition of all securities covered
by such registration statement.

                      (c) Furnish to the Holders such numbers of copies of a
prospectus, including a preliminary prospectus, in conformity with the
requirements of the Act, and such other documents as they may reasonably request
in order to facilitate the disposition of Registrable Securities owned by them.

                      (d) Use its best efforts to register and qualify the
securities covered by such registration statement under such other securities or
Blue Sky laws of such jurisdictions as shall be reasonably requested by the
Holders, provided that the Company shall not be required in connection therewith
or as a condition thereto to qualify to do business or to file a general consent
to service of process in any such states or jurisdictions.

                      (e) In the event of any underwritten public offering,
enter into and perform its obligations under an underwriting agreement, in usual
and customary form, with the managing underwriter of such offering. Each Holder
participating in such underwriting shall also enter into and perform its
obligations under such an agreement.

                      (f) Notify each Holder covered by such registration
statement at any time when a prospectus relating thereto is required to be
delivered under the Act of the happening of any event as a result of which the
prospectus included in such registration statement, as then in effect, includes
an untrue statement of a material fact or omits to state a material fact
required to be stated therein or necessary to make the statements therein not
misleading in the light of the circumstances then existing.

                      (g) Furnish, at the request of any Holder requesting
registration of Registrable Securities pursuant to this Section 1, on the date
that such Registrable Securities are delivered to the underwriters for sale in
connection with a registration pursuant to this Section 1, if such securities
are being sold through underwriters, or, if such securities are not being sold
through underwriters, on the date that the registration statement with respect
to such securities becomes

                                      -4-
<PAGE>   5

effective, an opinion, dated such date, of the counsel representing the Company
for the purposes of such registration, in form and substance as is customarily
given to underwriters in an underwritten public offering, addressed to the
underwriters, if any, and to the Holders requesting registration of Registrable
Securities.

               1.5 Furnish Information. It shall be a condition precedent to the
obligations of the Company to take any action pursuant to this Section 1 with
respect to the Registrable Securities of any selling Holder that such Holder
shall furnish to the Company such information regarding itself, the Registrable
Securities held by it, and the intended method of disposition of such securities
as shall be required to effect the registration of such Holder's Registrable
Securities.

               1.6 Expenses of Demand Registration. All expenses other than
underwriting discounts and commissions incurred in connection with
registrations, filings or qualifications pursuant to Section 1.2, including
(without limitation) all registration, filing and qualification fees, printers'
and accounting fees, fees and disbursements of counsel for the Company, and the
reasonable fees and disbursements of one counsel for the selling Holders (not to
exceed $25,000) shall be borne by the Company; provided, however, that the
Company shall not be required to pay for any expenses of any registration
proceeding begun pursuant to Section 1.2 if the registration request is
subsequently withdrawn at the request of the Holders holding a majority of the
Registrable Securities to be registered (in which case all participating Holders
shall bear such expenses pro rata on the basis of the number of shares for which
registration was requested), unless the Holders holding a majority of the
Registrable Securities agree to forfeit their right to one requested demand
registration pursuant to Section 1.2; provided further, however, that if at the
time of such withdrawal, the Holders have learned of a material adverse change
in the condition, business, or prospects of the Company from that known to the
Holders at the time of their request, then the Holders shall not be required to
pay any of such expenses and shall retain their rights pursuant to Section 1.2.

               1.7 Expenses of Company Registration. The Company shall bear and
pay all expenses incurred in connection with any registration, filing or
qualification of Registrable Securities with respect to the registrations
pursuant to Section 1.3 for each Holder (which right may be assigned as provided
in Section 1.13), including (without limitation) all registration, filing, and
qualification fees, printers and accounting fees relating or apportionable
thereto and the fees and disbursements of one counsel for the selling Holders
selected by them (not to exceed $25,000), but excluding underwriting discounts
and commissions relating to Registrable Securities.

               1.8 Underwriting Requirements. In connection with any offering
involving an underwriting of shares being issued by the Company, the Company
shall not be required under Section 1.3 to include any of the Holders'
securities in such underwriting unless they accept the terms of the underwriting
as agreed upon between the Company and the underwriters selected by it (or by
other persons entitled to select the underwriters), and then only in such
quantity as will not, in the opinion of the underwriters, jeopardize the success
of the offering by the Company, but in no event will other shareholder's
securities (other than Registrable Securities held by Holders or securities
being sold by the Company) be included in such offering if the amount of
Registrable Securities of any selling Holder included in the offering is reduced
or limited, and in no event will the amount of Registrable Securities of the
selling Holders included in the

                                      -5-
<PAGE>   6

offering be reduced below 20% of the total amount of securities included in such
offering (the Registrable Securities so included to be apportioned pro rata
among the selling Holders according to the total amount of Registrable
Securities entitled to be included therein owned by each selling Holder ,or in
such other proportions as shall mutually be agreed to by such selling Holders),
unless such offering is the initial public offering of the Company's securities,
in which case the selling Holders may be excluded entirely if the underwriters
make the determination described above and no other shareholder's securities are
included. For purposes of apportionment, any selling shareholder that is a
Holder of Registrable Securities and that is a partnership, limited liability
company or corporation, the partners, retired partners, members, retired members
and shareholders of such Holder, or the estates and family members of any such
partners, retired partners, members and retired members and any trusts for the
benefit of any of the foregoing persons shall be deemed to be a single "selling
shareholder," and any pro rata reduction with respect to such "selling
shareholder" shall be based upon the aggregate amount of shares carrying
registration rights owned by all entities and individuals included in such
"selling shareholder," as defined in this sentence.

        The Company shall have the right to include shares now or hereafter
owned by the Company's officers and employee directors that are not already, by
virtue of this Agreement, deemed Registrable Securities (the "Management
Shares") in any registration pursuant to Section 1.3, provided, however, that
all of the Management Shares shall be excluded from such registration before any
Registrable Securities are excluded from such registration pursuant to Section
1.8 hereof. If Management Shares are included in a registration pursuant to
Section 1.3, each holder of Management Shares will be deemed a "Holder" (as that
term is defined in Section 1 of this Agreement) for all purposes under this
Agreement pertaining to such registration.

               1.9 Delay of Registration. No Holder shall have any right to
obtain or seek an injunction restraining or otherwise delaying any such
registration as the result of any controversy that might arise with respect to
the interpretation or implementation of this Section 1.

               1.10 Indemnification. In the event any Registrable Securities are
included in a registration statement under this Section 1:

                      (a) To the extent permitted by law, the Company will
indemnify and hold harmless each Holder, any underwriter (as defined in the Act)
for such Holder and each person, if any, who controls such Holder or underwriter
within the meaning of the Act or the Securities Exchange Act of 1934, amended
(the "1934 Act"), against any losses, claims, damages, or liabilities (joint or
several) to which they may become subject under the Act, the 1934 Act or other
federal or state law, insofar as such losses, claims, damages, or liabilities
(or actions in respect thereof) arise out of or are based upon any of the
following statements, omissions or violations (collectively a "Violation"): (i)
any untrue statement or alleged untrue statement of a material fact contained in
such

                                      -6-
<PAGE>   7

registration statement, including any preliminary prospectus or final prospectus
contained therein or any amendments or supplements thereto, (ii) the omission or
alleged omission to state therein a material fact required to be stated therein,
or necessary to make the statements therein not misleading, or (iii) any
violation or alleged violation by the Company of the Act, the 1934 Act, any
state securities law or any rule or regulation promulgated under the Act, the
1934 Act or any state securities law; and the Company will pay to each such
Holder, underwriter or controlling person, as incurred, any legal or other
expenses reasonably incurred by them in connection with investigating or
defending any such loss, claim, damage, liability, or action; provided, however,
that the indemnity agreement contained in this Section 1.10(a) shall not apply
to amounts paid in settlement of any such loss, claim, damage, liability, or
action if such settlement is effected without the consent of the Company (which
consent shall not be unreasonably withheld), nor shall the Company be liable in
any such case for any such loss, claim, damage, liability, or action to the
extent that it arises out of or is based upon a Violation that occurs in
reliance upon and in conformity with written information furnished expressly for
use in connection with such registration by any such Holder, underwriter or
controlling person.

                      (b) To the extent permitted by law, each selling Holder
will indemnify and hold harmless the Company, each of its directors, each of its
officers who has signed the registration statement, each person, if any, who
controls the Company within the meaning of the Act, any underwriter, any other
Holder selling securities in such registration statement and any controlling
person of any such underwriter or other Holder, against any losses, claims,
damages, or liabilities (joint or several) to which any of the foregoing persons
may become subject, under the Act, the 1934 Act or other federal or state law,
insofar as such losses, claims, damages, or liabilities (or actions in respect
thereto) arise out of or are based upon any Violation, in each case to the
extent (and only to the extent) that such Violation occurs in reliance upon and
in conformity with written information furnished by such Holder expressly for
use in connection with such registration; and each such Holder will pay, as
incurred, any legal or other expenses reasonably incurred by any person intended
to be indemnified pursuant to this Section 1.10(b), in connection with
investigating or defending any such loss, claim, damage, liability, or action;
provided, however, that the indemnity agreement contained in this Section
1.10(b) shall not apply to amounts paid in settlement of any such loss, claim,
damage, liability or action if such settlement is effected without the consent
of the Holder, which consent shall not be unreasonably withheld; and provided
further, that, in no event shall any indemnity under this Section 1.10(b) exceed
the net proceeds from the offering received by such Holder.

                      (c) Promptly after receipt by an indemnified party under
this Section 1.10 of notice of the commencement of any action (including any
governmental action), such indemnified party will, if a claim in respect thereof
is to be made against any indemnifying party under this Section 1.10, deliver to
the indemnifying party a written notice of the commencement thereof and the
indemnifying party shall have the right to participate in, and, to the extent
the indemnifying party so desires, jointly with any other indemnifying party
similarly noticed, to assume the defense thereof with counsel mutually
satisfactory to the parties; provided, however, that an indemnified party shall
have the right to retain its own counsel, with the fees and expenses to be paid
by the indemnifying party, if representation of such indemnified party by the
counsel retained by the indemnifying party would be inappropriate due to actual
or potential differing interests between such indemnified party

                                      -7-
<PAGE>   8

and any other party represented by such counsel in such proceeding. The failure
to deliver written notice to the indemnifying party within a reasonable time of
the commencement of any such action, to the extent prejudicial to its ability to
defend such action, shall relieve such indemnifying party of any liability to
the indemnified party under this Section 1.10 to the extent of any liability
attributable to the failure to timely deliver such notice, but the omission so
to deliver written notice to the indemnifying party will not relieve it of any
liability that it may have to any indemnified party otherwise than under this
Section 1.10.

                      (d) If the indemnification provided for in this Section
1.10 is held by a court of competent jurisdiction to be unavailable to an
indemnified party with respect to any loss, liability, claim, damage or expense
referred to therein, then the indemnifying party, in lieu of indemnifying such
indemnified party hereunder, shall contribute to the amount paid or payable by
such indemnified party as a result of such loss, liability, claim, damage or
expense in such proportion as is appropriate to reflect the relative fault of
the indemnifying party on the one hand and of the indemnified party on the other
in connection with the statements or omissions that resulted in such loss,
liability, claim, damage or expense as well as any other relevant equitable
considerations; provided, that, in no event shall any contribution by a Holder
under this Section 1.10(d) exceed the net proceeds from the offering received by
such Holder. The relative fault of the indemnifying party and of the indemnified
party shall be determined by reference to, among other things, whether the
untrue or alleged untrue statement of a material fact or the omission to state a
material fact relates to information supplied by the indemnifying party or by
the indemnified party and the parties' relative intent, knowledge, access to
information and opportunity to correct or prevent such statement or omission.

                      (e) Notwithstanding the foregoing, to the extent that the
provisions on indemnification and contribution contained in the underwriting
agreement entered into in connection with the underwritten public offering are
in conflict with the foregoing provisions, the provisions in the underwriting
agreement shall control.

                      (f) The obligations of the Company and Holders under this
Section 1.10 shall survive the completion of any offering of Registrable
Securities in a registration statement under this Section 1, and otherwise.

               1.11 Reports Under Securities Exchange Act of 1934. With a view
to making available to the Holders the benefits of Rule 144 promulgated under
the Act and any other rule or regulation of the SEC that may at any time permit
a Holder to sell securities of the Company to the public without registration or
pursuant to a registration on Form S-3, the Company agrees to:

                      (a) make and keep public information available, as those
terms are understood and defined in SEC Rule 144 or any similar or analogous
Rule promulgated under the Securities Act, at all times after the effective date
of the first registration statement filed by the Company for the offering of its
securities to the general public;

                      (b) take such action, including the voluntary registration
of its Common Stock under Section 12 of the 1934 Act, as is necessary to enable
the Holders to utilize Form S-3 for

                                      -8-
<PAGE>   9

the sale of their Registrable Securities, such action to be taken as soon as
practicable after the end of the fiscal year in which the first registration
statement filed by the Company for the offering of its securities to the general
public is declared effective;

                      (c) file with the SEC in a timely manner all reports and
other documents required of the Company under the Act and the 1934 Act; and

                      (d) furnish to any Holder, so long as the Holder owns any
Registrable Securities, forthwith upon request (i) a written statement by the
Company that it has complied with the reporting requirements of SEC Rule 144 (at
any time after 90 days after the effective date of the first registration
statement filed by the Company), the Act and the 1934 Act (at any time after it
has become subject to such reporting requirements), or that it qualifies as a
registrant whose securities may be resold pursuant to Form S-3 (at any time
after it so qualifies), (ii) a copy of the most recent annual or quarterly
report of the Company and such other reports and documents so filed by the
Company, and (iii) such other information as may be reasonably requested in
availing any Holder of any rule or regulation of the SEC that permits the
selling of any such securities without registration or pursuant to such form.

               1.12 Form S-3 Registration. In case the Company shall receive
from any Holder or Holders of Registrable Securities, a written request or
requests that the Company effect a registration on Form S-3 and any related
qualification or compliance with respect to all or a part of the Registrable
Securities owned by such Holder or Holders, the Company will:

                      (a) promptly give written notice of the proposed
registration, and any related qualification or compliance, to all other Holders;
and

                      (b) as soon as practicable, effect such registration and
all such qualifications and compliances as may be so requested and as would
permit or facilitate the sale and distribution of all or such portion of such
Holder's or Holders' Registrable Securities as are specified in such request,
together with all or such portion of the Registrable Securities of any other
Holder or Holders joining in such request as are specified in a written request
given within 15 days after receipt of such written notice from the Company;
provided, however, that the Company shall not be obligated to effect any such
registration, qualification or compliance, pursuant to this Section 1.12: (1) if
Form S-3 is not available for such offering by the Holders; (2) if the Holders,
together with the holders of any other securities of the Company entitled to
inclusion in such registration, propose to sell Registrable Securities and such
other securities (if any) at an aggregate price to the public (net of any
underwriters' discounts or commissions) of less than $10,000,000; (3) if the
Company shall furnish to the Holders a certificate signed by the President of
the Company stating that in the good faith judgment of the Board of Directors of
the Company, it would be seriously detrimental to the Company and its
shareholders for such Form S-3 Registration to be effected at such time, in
which event the Company shall have the right to defer the filing of the Form S-3
registration statement for a period of not more than 120 days after receipt of
the request of the Holder or Holders under this Section 1.12; provided, however,
that the Company shall not utilize this right more than once in any 12 month
period; (4) more than twice in any 12 month period; (5) more than three times;
or (6) in any particular jurisdiction in which the Company would be required to
qualify to do business or to

                                      -9-
<PAGE>   10

execute a general consent to service of process in effecting such registration,
qualification or compliance.

                      (c) If the Holders initiating the registration request
hereunder (the "Participating Holders") intend to distribute the Registrable
Securities covered by their request by means of an underwriting, they shall so
advise the Company as part of their request made pursuant to this Section 1.12
and the Company shall include such information in the written notice referred to
in Section 1.12(a). In such event, the right of any Holder to include such
Holder's Registrable Securities in such registration shall be conditioned upon
such Holder's participation in such underwriting and the inclusion of such
Holder's Registrable Securities in the underwriting (unless otherwise mutually
agreed by a majority in interest of the Participating Holders and such Holder)
to the extent provided herein. All Holders proposing to distribute their
securities through such underwriting shall (together with the Company as
provided in Section 1.4(e)) enter into an underwriting agreement in customary
form with the underwriter or underwriters selected for such underwriting by a
majority in interest of the Participating Holders. Notwithstanding any other
provision of this Section 1.12, if the underwriter advises the Participating
Holders in writing that marketing factors require a limitation of the number of
shares to be underwritten, then the Participating Holders shall so advise all
Holders of Registrable Securities that would otherwise be underwritten pursuant
hereto, and the number of shares of Registrable Securities that may be included
in the underwriting shall be allocated first among the Participating Holders
and, after all Registrable Securities owned by the Participating Holders and
included in the request for registration pursuant to Section 1.12 have been
included, then among all other Holders thereof, including the Participating
Holders to the extent Registrable Securities held by them were not included in
the request for registration pursuant to Section 1.12, in proportion (as nearly
as practicable) to the amount of Registrable Securities of the Company owned by
each Holder. In no event shall other shareholder's securities (other than
Registrable Securities held by Holders) be included in such offering if the
amount of Registrable Securities of any selling Holder included in the offering
is reduced or limited.

                      (d) Subject to the foregoing, the Company shall file a
registration statement covering the Registrable Securities and other securities
so requested to be registered as soon as practicable after receipt of the
request or requests of the Holders. All expenses incurred in connection with a
registration requested pursuant to Section 1.12, including (without limitation)
all registration, filing, qualification, printer's and accounting fees and the
reasonable fees and disbursements of one counsel for the selling Holder or
Holders (not to exceed $25,000) and counsel for the Company, but excluding any
underwriters' discounts or commissions associated with Registrable Securities,
shall be borne by the Company. Registrations effected pursuant to this Section
1.12 shall not be counted as the demand for registration or registrations
effected pursuant to Sections 1.2 or 1.3, respectively.

               1.13 Assignment of Registration Rights. The rights to cause the
Company to register Registrable Securities pursuant to this Section 1 may be
assigned by a Holder to any (a) transferee or assignee who acquires at least
500,000 shares of Registrable Securities (as adjusted for stock splits,
combinations and the like), (b) partner or retired partner of any Holder that is
a partnership, (c) member or former member of a Holder that is a limited
liability company, (d) family

                                      -10-
<PAGE>   11

member or trust for the benefit of any individual Holder, or (e) any fund,
investment vehicle or other affiliated entity controlled by a Holder (each a
"Transferee") regardless of the number of shares acquired by such Transferee
under clauses (b) through (e), provided the Company is, within a reasonable time
after such transfer, furnished with written notice of the name and address of
such transferee or assignee and the securities with respect to which such
registration rights are being assigned; and provided, further, that such
assignment shall be effective only if immediately following such transfer the
further disposition of such securities by the transferee or assignee is
restricted under the Act. Notwithstanding the above, such rights may be assigned
by a Holder to a parent, subsidiary, limited partner, general partner or other
affiliate of a Holder ( the "Transferee") regardless of the number of shares
acquired by such Transferee.

               1.14 "Market Stand-Off" Agreement. Each holder of securities that
are or at one time were Registrable Securities (or that are or were convertible
into Registrable Securities) hereby agrees that, during a period not to exceed
180 days, following the effective date of the Initial Registration of the
Company, it shall not sell or otherwise transfer or dispose of (other than to a
donee who agrees to be similarly bound) any Common Stock of the Company held by
it at any time during such period except (i) Common Stock included in such
registration or (ii) Common Stock acquired in open market transactions following
such registration; provided, however, that:

                      (a) such agreement shall be applicable only to the first
such registration statement of the Company that covers Common Stock (or other
securities) to be sold on its behalf to the public in an underwritten offering;
and

                      (b) all executive officers and directors of the Company
who hold shares of the Company's voting securities enter into similar
agreements.

        In order to enforce the foregoing covenant, the Company may impose
stop-transfer instructions with respect to the Registrable Securities of each
Holder (and the shares or securities of every other person subject to the
foregoing restriction) until the end of such period.

               1.15 Termination of Registration Rights. No shareholder shall be
entitled to exercise any right provided for in this Section 1 after the earlier
of (i) five years following the consummation of the sale of securities pursuant
to a registration statement filed by the Company under the Act in connection
with the initial firm commitment underwritten offering of its securities to the
general public, or (ii) as to a given Holder (together with its affiliates,
partners and former partners), when such Holder can sell all of such Holder's
Registrable Securities in a 90-day period pursuant to Rule 144 promulgated under
the Act.

        2.     Information Rights.

               2.1 Inspection. The Company shall permit each Holder holding,
together with its affiliates, an aggregate of 500,000 shares of the Registrable
Securities (as adjusted for stock splits and combinations), at such Holder's
expense to visit and inspect the Company's properties, to examine its books of
account and records and to discuss the Company's affairs, finances and accounts
with its officers, all at such reasonable times as may be requested by the
Holder; provided,

                                      -11-
<PAGE>   12

however, that the Company shall not be obligated pursuant to this Section 2.1 to
provide access to any information that it reasonably considers to be a trade
secret or similar confidential information unless such Holder agrees in writing
to hold such information in confidence.

               2.2 Delivery of Financial Statements. The Company shall deliver
(unless otherwise notified by a Holder that it does not wish to receive such
materials) to each Holder that holds, together with its affiliates, an aggregate
of 500,000 shares of Registrable Securities (as adjusted for stock splits and
combinations):

                      (a) as soon as practicable, but in any event within 90
days after the end of each fiscal year of the Company commencing with the fiscal
year ending December 31, 1999, a balance sheet, and statements of operations and
cash flow for such fiscal year. Such year-end financial reports are to be in
reasonable detail, prepared in accordance with generally accepted accounting
principles ("GAAP"), and audited and certified by independent public accountants
of nationally recognized standing selected by the Company;

                      (b) within 45 days of the end of each fiscal quarter of
the Company commencing with the fiscal quarter ending September 30, 1999, an
unaudited statement of operations and balance sheet for and as of the end of
such quarter (including, through the fiscal quarter ending December 31, 1999,
comparisons to annual financial plans and to comparable fiscal year 1998
periods), in reasonable detail and prepared in accordance with GAAP, subject to
year end audit adjustments and the absence of footnotes; and

                      (c) beginning in the first month of the fiscal year ending
December 31, 2000, an unaudited monthly financial report comparing the Company's
monthly results to those in the Company's annual plan and to the prior year's
comparable period.

                      (d) beginning with the fiscal year 2000, (i) not later
than 45 days after the beginning of each fiscal year, an annual financial plan
in reasonable detail for such fiscal year (and as soon as reasonably available,
subsequent revisions thereto); and (ii) as soon as practicable after the end of
each month, and in any event within 20 days thereafter, a balance sheet of the
Company as of the end of each such month, and a statement of income and a
statement of cash flows of the Company for such month and for the current fiscal
year to date, including a comparison to plan figures for such period, prepared
in accordance with generally accepted accounting principles consistently
applied, with the exception that no notes need be attached to such statements
and year-end audit adjustments may not have been made.

               2.3 Termination of Information Rights. The covenants set forth in
this Section 2 shall terminate as to Holders and be of no further force and
effect (i) upon the consummation of the sale of securities pursuant to a
registration statement filed by the Company under the Act in connection with the
initial firm commitment underwritten offering of its securities to the general
public or (ii) when the Company first becomes subject to the periodic reporting
requirements of Section 12(g) or 15(d) of the Securities Exchange Act of 1934,
whichever event shall first occur.

        3.     Investors' Right of First Refusal.

                                      -12-
<PAGE>   13

               3.1 Right of First Refusal upon Issuances of Securities by the
Company.

                      (a) The Company hereby grants, on the terms set forth in
this Section 3.1, to each Investor who holds in the aggregate at least 500,000
shares of Common Stock issuable or issued upon conversion of Series B Preferred
Stock and Series C Preferred Stock the right of first refusal to purchase all or
any part of such Investor's pro rata share of the New Securities (as defined in
Section 3.1(b)) that the Company may, from time to time, propose to sell and
issue. The Investors may purchase said New Securities on the same terms and at
the same price at which the Company proposes to sell the New Securities. The pro
rata share of each Investor, for purposes of this right of first refusal, is the
ratio of the total number of shares of Common Stock issued or issuable upon
conversion of Series B Preferred Stock and Series C Preferred Stock held by such
Investor, to the total number of shares of Common Stock outstanding immediately
prior to the issuance of the New Securities (including any shares of Common
Stock into which outstanding shares of Preferred Stock are convertible). If not
all eligible Investors elect to purchase their pro rata share of the New
Securities, then the Company shall promptly notify in writing the eligible
Investors who do so elect and shall offer such eligible Investors the right to
acquire such unsubscribed shares. If all such eligible Investors entitled to
such notice, in the aggregate, choose to purchase more than the unsubscribed
shares, then such unsubscribed shares shall be allocated among the eligible
Investors pro rata on the basis of the number of shares of Common Stock issuable
or issued upon conversion of Series B Preferred Stock and Series C Preferred
Stock owned by such eligible Investors. For purposes of this Section 3.1, if any
"investment company" (as defined in the Investment Company Act of 1940, as
amended (the "1940 Act")) together with other investment companies advised by
the same investment advisor holds more than 500,000 shares of Common Stock
issuable or issued upon conversion of Series B Preferred Stock and Series C
Preferred Stock then each such investment company shall have the rights
described in this Section 3.1.

                      (b) "New Securities" shall mean any capital stock of the
Company, whether now authorized or not, and any rights, options or warrants to
purchase said capital stock, and securities of any type whatsoever that are, or
may become, convertible into said capital stock; provided that "New Securities"
does not include (i) the Registrable Securities, (ii) securities offered
pursuant to a registration statement filed under the Act, (iii) securities
issued pursuant to the acquisition of another corporation by the Company by
merger, purchase of substantially all of the assets of such corporation or other
reorganization that have been approved by the board of directors, (iv)
15,086,235 shares of Common Stock or other securities issued or issuable to
officers, directors or employees of the Company pursuant to any plan or
arrangement approved by the board of directors of the Company, (v) all shares of
Common Stock or other securities issued or issuable to scientific advisors or
consultants of the Company pursuant to any plan or arrangement approved by the
board of directors of the Company, (vi) all securities issued, upon the approval
of the board of directors of the Company, pursuant to agreements to license
technology and/or provide sponsored research that have been approved by the
board of directors, and (vii) all shares of Common Stock or other securities
issued in connection with lending, equipment leasing or equipment financing
arrangements approved by the board of directors of the Company.

                                      -13-
<PAGE>   14

                      (c) In the event the Company proposes to undertake an
issuance of New Securities, it shall give to the Investors written notice (the
"Notice") of its intention, describing the type of New Securities, the price,
the terms upon which the Company proposes to issue the same, and a statement as
to the number of days from receipt of such Notice within which the Investors
must respond to such Notice. The Investors shall have 30 days from the date of
receipt of the Notice to purchase any or all of the New Securities for the price
and upon the terms specified in the Notice by giving written notice to the
Company and stating therein the quantity of New Securities to be purchased and
forwarding payment for such New Securities to the Company if immediate payment
is required by such terms, or in any event no later than 30 days after the date
of receipt of the Notice.

                      (d) In the event the Investors fail to exercise in full
the right of first refusal within said 30 day period, the Company shall have 90
days thereafter to sell or enter into an agreement (pursuant to which the sale
of New Securities covered thereby shall be closed, if at all, within 30 days
from date of said agreement) to sell the New Securities respecting which the
Investors' rights were not exercised, at a price and upon general terms no more
favorable to the purchasers thereof than specified in the Notice. In the event
the Company has not sold the New Securities within said 90-day period (or sold
and issued New Securities in accordance with the foregoing within 30 days from
the date of said agreement), the Company shall not thereafter issue or sell any
New Securities without first offering such securities to the Investors in the
manner provided above.

                      (e) The right of first refusal granted under this Section
3.1 shall expire upon:

                                 (i) The closing of the Company's first firm
commitment underwritten public offering pursuant to an effective registration
statement filed by the Company under the Act.

                                 (ii) For each Investor, the date on which such
Investor no longer holds a minimum aggregate of 500,000 shares of Series B
Preferred Stock and Series C Preferred Stock.

        4.     Miscellaneous Provisions.

                                      -14-
<PAGE>   15
 4.1 Waivers and Amendments. Any term of this Agreement may be amended and the
observance of any term of this Agreement may be waived (either generally or in a
particular instance and either retroactively or prospectively), only with the
written consent of the Company and the holders of at least a majority of the
shares of Registrable Securities. Any amendment or waiver effected in accordance
with this Section 4.1 shall be binding upon each person or entity that is
granted certain rights under this Agreement and the Company; provided, however,
that any amendment to Section 1.14 hereof shall not be effective as to any
"investment company" (as defined in the 1940 Act) without the consent of such
investment company.

               4.2 Notices. All notices and other communications required or
permitted hereunder shall be in writing and, except as otherwise noted herein,
shall be deemed effectively given upon personal delivery, delivery by nationally
recognized courier or upon deposit with the United States Post Office, (by first
class mail, postage prepaid) addressed: (a) if to the Company, at the address
set forth on the first page of this Agreement (or at such other address as the
Company shall have furnished to the Holders in writing) attention of Chief
Executive Officer and (b) if to a Holder, at the latest address of such person
shown on the Company's records.

               4.3 Descriptive Headings. The descriptive headings herein have
been inserted for convenience only and shall not be deemed to limit or otherwise
affect the construction of any provisions hereof.

               4.4 Governing Law. This Agreement shall be governed by and
interpreted under the laws of the State of California as applied to agreements
among California residents, made and to be performed entirely within the State
of California.

               4.5 Counterparts. This Agreement may be executed in one or more
counterparts, each of which shall for all purposes be deemed to be an original
and all of which shall constitute the same instrument, but only one of which
need be produced.

               4.6 Expenses. If any action at law or in equity is necessary to
enforce or interpret the terms of this Agreement, the prevailing party shall be
entitled to reasonable attorney's fees, costs and necessary disbursements in
addition to any other relief to which such party may be entitled.

               4.7 Successors and Assigns. Except as otherwise expressly
provided in this Agreement, this Agreement shall benefit and bind the
successors, assigns, heirs, executors and administrators of the parties to this
Agreement.

               4.8 Entire Agreement. This Agreement constitutes the full and
entire understanding and agreement between the parties with regard to the
subject matter of this Agreement.

                                      -15-
<PAGE>   16

               4.9 Separability; Severability. Unless expressly provided in this
Agreement, the rights of each Holder under this Agreement are several rights,
not rights jointly held with any other Holders. Any invalidity, illegality or
limitation on the enforceability of this Agreement with respect to any Holder
shall not affect the validity, legality or enforceability of this Agreement with
respect to the other Holders. If any provision of this Agreement is judicially
determined to be invalid, illegal or unenforceable, the validity, legality and
enforceability of the remaining provisions shall not be affected or impaired.

               4.10 Stock Splits. All references to numbers of shares in this
Agreement shall be appropriately adjusted to reflect any stock dividend, split,
combination or other recapitalization of shares by the Company occurring after
the date of this Agreement.

               4.11 Aggregation of Stock. All shares of the Preferred Stock held
or acquired by affiliated entities or persons (including investment funds,
partnerships and other entities managed or controlled by any Holder) shall be
aggregated together for the purpose of determining the availability of any
rights under this Agreement.

                  [Remainder of page intentionally left blank]

                                      -16-
<PAGE>   17

        IN WITNESS WHEREOF, the parties have executed this Amended and Restated
Investors Rights Agreement on the day and year first set forth above.

                                  "COMPANY"

                                  COLO.COM

                                  By:  /s/ Charles M. Skibo
                                     -------------------------------------------
                                      Charles M. Skibo, Chief Executive Officer

<PAGE>   18

                                  "HOLDERS"

                                  Name:      COLO.COM EQUITY LIMITED
                                       -----------------------------------------

                                  Signature:  /s/ Sydney J. Coleman
                                            ------------------------------------

                                  Title:     The Director Ltd., Director
                                        ----------------------------------------

<PAGE>   19

                                  "HOLDERS"

                                  DUFF ACKERMAN & GOODRICH, L.P. DAG LLC

                                  Signature: /s/ John M. Duff, Jr.
                                            ------------------------------------

                                  Title:     Managing Director
                                        ----------------------------------------

                                  DUFF ACKERMAN & GOODRICH QP FUND L.P. DAG LLC

                                  Signature: /s/ John M. Duff, Jr.
                                            ------------------------------------

                                  Title:     Managing Director
                                        ----------------------------------------

                                  DUFF ACKERMAN & GOODRICH CD FUND, L.P. DAG LLC

                                  Signature: /s/ John M. Duff, Jr.
                                            ------------------------------------

                                  Title:     Managing Director
                                        ----------------------------------------

                                  DAG GP FUND, LLC DAG LLC

                                  Signature: /s/ John M. Duff, Jr.
                                            ------------------------------------

                                  Title:     Managing Director
                                        ----------------------------------------

<PAGE>   20

                                  "HOLDERS"

                                  MeriTech Capital Partners L.P.

                                  By: MeriTech Capital Associates L.L.C.
                                      its General Partner

                                  By: MeriTech Management Associates L.L.C.
                                      a managing member

                                  By:   /s/ Paul S. Madera
                                     -------------------------------------------
                                      Paul S. Madera, a managing member

                                  MeriTech Capital Affiliates L.P.

                                  By: MeriTech Capital Associates L.L.C.
                                      its General Partner

                                  By: MeriTech Management Associates L.L.C.
                                      a managing member

                                  By:   /s/ Paul S. Madera
                                     -------------------------------------------
                                      Paul S. Madera, a managing member

<PAGE>   21

                                  "HOLDERS"

                                  Menlo Ventures VIII, L.P.
                                  By: MV Management VIII, L.L.C.
                                      Its General Partner

                                  By:  /s/ John L. Jarve
                                     -------------------------------------------
                                      Managing Member

                                  Menlo Entrepreneurs Fund VIII, L.P.
                                  By: MV Management VIII, L.L.C.
                                      Its General Partner

                                  By:  /s/ John L. Jarve
                                     -------------------------------------------
                                      Managing Member

                                  MMEF VIII, L.P.
                                  By: MV Management VIII, L.L.C.
                                      Its General Partner

                                  By:  /s/ John L. Jarve
                                     -------------------------------------------
                                      Managing Member

                                  Menlo Ventures VII, L.P.
                                  By: MV Management VII, L.L.C.
                                      Its General Partner

                                  By:  /s/ John L. Jarve
                                     -------------------------------------------
                                      Managing Member

                                  Menlo Entrepreneurs Fund VII, L.P.
                                  By: MV Management VII, L.L.C.
                                      Its General Partner

                                  By:  /s/ John L. Jarve
                                     -------------------------------------------
                                      Managing Member

<PAGE>   22

                                  "HOLDERS"

                                  PIVOTAL PARTNERS, L.P.

                                  By:     /s/ Ralph Cechettini
                                     -------------------------------------------

                                  Name:   Ralph Cechettini
                                       -----------------------------------------

                                  Title:  Manager
                                        ----------------------------------------

<PAGE>   23

                                  "HOLDERS"

                                  CALIFORNIA BANK & TRUST AGENT FOR RALPH H.
                                  CECHETTINI IRA #1

                                  By: /s/ Novenia R. Baines
                                     -------------------------------------------

                                  Name: Novenia R. Baines
                                       -----------------------------------------

                                  Title: Trust Officer
                                        ----------------------------------------

<PAGE>   24

                                  "HOLDERS"

                                  CHRISTOPHER LORD

                                  Signature:  /s/ Christopher Lord
                                            ------------------------------------

<PAGE>   25

                                  "HOLDERS"

                                  KEVIN LINKER

                                  Signature:  /s/ Kevin Linker
                                            ------------------------------------

<PAGE>   26

                                  "HOLDERS"

                                  SELIGMAN COMMUNICATIONS
                                  AND INFORMATION FUND, INC.

                                  By:  J. & W. Seligman & Co. Incorporated,
                                       its investment advisor

                                  By:  /s/ unreadable
                                      ------------------------------------------
                                       Name:
                                       Title:

                                  SELIGMAN INVESTMENT OPPORTUNITIES
                                  (MASTER) FUND-NTV PORTFOLIO

                                  By:  J. & W. Seligman & Co. Incorporated,
                                       its investment advisor

                                  By:  /s/ unreadable
                                      ------------------------------------------
                                       Name:
                                       Title:

                                  SELIGMAN NEW TECHNOLOGIES
                                  FUND, INC.

                                  By:  J. & W. Seligman & Co. Incorporated,
                                       its investment advisor

                                  By:  /s/ unreadable
                                      ------------------------------------------
                                       Name:
                                       Title:
<PAGE>   27
"HOLDERS"

Name: Diablo Capital
      -----------------------------
Signature: /s/ Kevin J. Senn
           ------------------------
Name of Signer: Kevin J. Senn
                -------------------
Title: Member
       ----------------------------
<PAGE>   28
"HOLDERS"

Name: Walnut Creek Ventures, LLC
      -----------------------------------
Signature: /s/ unreadable, /s/ unreadable
           ------------------------------
Name of Signer:
                -------------------------
Title: Member(s)
       ----------------------------------
<PAGE>   29
"HOLDERS"

Name: Michael Hirtenstein
      -----------------------------
Signature: /s/ Michael Hirtenstein
           ------------------------
Name of Signer:
                -------------------
Title:
       ----------------------------
<PAGE>   30
                              "HOLDERS"

                              Accel VI L.P.
                              By: Accel VI Associates L.L.C.
                              Its General Partner

                              By: /s/ unreadable
                                  ---------------------------------
                                  Managing Member

                              Accel Internet Fund II L.P.
                              By: Accel Internet Fund II Associates L.L.C.
                              Its General Partner

                              By: /s/ unreadable
                                  ---------------------------------
                                  Managing Member

                              Accel Keiretsu VI L.P.
                              By: Accel Keiretsu VI Associates L.L.C.
                              Its General Partner

                              By: /s/ unreadable
                                  ---------------------------------
                                  Managing Member

                              Accel Investors '98 L.P.

                              By: /s/ unreadable
                                  ---------------------------------
                                  General Partner

<PAGE>   31

Exhibit 10.1

                                               "HOLDERS"

                                               Name: Athena Venturefund, LP
                                                     --------------------------
                                               Signature: /s/ unreadable
                                                          ---------------------
                                               Title: General Partner
                                                      -------------------------

<PAGE>   32
                              "HOLDERS"

                              Name: COMDISCO, INC.
                                   ---------------------------------------

                              Signature: /s/ James P. Labe
                                        ----------------------------------

                              Name of Signer: James P. Labe
                                             -----------------------------

                              Title: President, Comdisco Ventures Division
                                    --------------------------------------
<PAGE>   33
                              "HOLDERS"

                              Name: Chul S. Ha
                                   ---------------------------------------

                              Signature: /s/ Chul S. Ha
                                        ----------------------------------

                              Title:
                                    --------------------------------------
<PAGE>   34
                              "HOLDERS"

                              Name: Daniel A. Duc
                                   ---------------------------------------

                              Signature: /s/ Daniel A. Duc
                                        ----------------------------------

                              Title: Individual
                                    --------------------------------------
<PAGE>   35
                              "HOLDERS"

                              Name: Ridgecrest Development Company, Inc.,
                                    a California corporation
                                   ---------------------------------------

                              Signature: /s/ Pamela J. Bishop
                                        ----------------------------------

                              Name of Signer: Pamela J. Bishop
                                             -----------------------------

                              Title: Secretary/Treasurer
                                    --------------------------------------
<PAGE>   36
                              "HOLDERS"

                              HENRY KOERNER III

                              Signature: /s/ Henry Koerner III
                                        ----------------------------------
<PAGE>   37
                              "HOLDERS"

                              Name: MasTec, Inc.
                                   ---------------------------------------

                              Signature: /s/ unreadable
                                        ----------------------------------

                              Title: Vice President
                                    --------------------------------------
<PAGE>   38
                              "HOLDERS"

                              Highland Capital Partners IV
                              Limited Partnership

                              By: Highland Management Partners IV LLC,
                                  Its General Partner

                              By: /s/ unreadable
                                 -------------------------------------
                                      Member

                              Highland Entrepreneurs' Fund IV
                              Limited Partnership

                              By: Highland Entrepreneurs' Fund IV LLC,
                                  Its General Partner

                              By: /s/ unreadable
                                 -------------------------------------
                                      Member
<PAGE>   39
                              "HOLDERS"

                              Name: Power Co Partnership
                                   ---------------------------------------

                              Signature: /s/ unreadable
                                        ----------------------------------

                              Title: Partner
                                    --------------------------------------
<PAGE>   40
                              "HOLDERS"

                              Name: Skanska (USA) Inc.
                                   ---------------------------------------

                              Signature: /s/ Stuart E. Graham
                                        ----------------------------------

                              Name of Signer: Stuart E. Graham
                                             -----------------------------

                              Title: President, C.E.O.
                                    --------------------------------------
<PAGE>   41
                              "HOLDERS"

                              Name: SF Ventures I, LLC
                                   ---------------------------------------

                              Signature: /s/ Brent N. Folland
                                        ----------------------------------

                              Name of Signer: Brent N. Folland
                                             -----------------------------

                              Title: Manager
                                    --------------------------------------
<PAGE>   42
                              "HOLDERS"

                              Name: Vertex Capital II LLC
                                   ---------------------------------------

                              Signature: /s/ unreadable
                                        ----------------------------------

                              Title:
                                    --------------------------------------
<PAGE>   43
                              "HOLDERS"

                              Name: Amerindo Technology Growth Fund II
                                   ---------------------------------------

                              Signature: /s/ Gary A. Tanaka
                                        ----------------------------------

                              Name of Signer: Gary A. Tanaka
                                             -----------------------------

                              Title: Director
                                    --------------------------------------

                              Name: Litton Master Trust
                                   ---------------------------------------

                              Signature: /s/ Gary A. Tanaka
                                        ----------------------------------

                              Title: Attorney in Fact
                                     Gary A. Tanaka
                                    --------------------------------------
<PAGE>   44
                              "HOLDERS"

                              Name: James Stableford
                                   ---------------------------------------

                              Signature: /s/ James Stableford
                                        ----------------------------------

                              Title:
                                    --------------------------------------
<PAGE>   45
                              "HOLDERS"

                              Name: Matthew O. Fitzmaurice
                                   ---------------------------------------

                              Signature: /s/ Matthew O. Fitzmaurice
                                        ----------------------------------

                              Title:
                                    --------------------------------------
<PAGE>   46
                              "HOLDERS"

                              Name: Emeric J. McDonald
                                   ---------------------------------------

                              Signature: /s/ Emeric J. McDonald
                                        ----------------------------------

                              Title:
                                    --------------------------------------
<PAGE>   47
                              "HOLDERS"

                              Name: Jun Woo Bae
                                   ---------------------------------------

                              Signature: /s/ Bae Jun Woo
                                        ----------------------------------

                              Title:
                                    --------------------------------------
<PAGE>   48
                              "HOLDERS"

                              Name: GC&H Investments
                                   ---------------------------------------

                              Signature: /s/ John L. Cardoza
                                        ----------------------------------

                              Name of Signer: John L. Cardoza
                                             -----------------------------

                              Title: Executive Partner
                                    --------------------------------------
<PAGE>   49
                              "HOLDERS"

                              Name: Hikari Tsushin Partners, L.P.
                                   ---------------------------------------

                              By: Its General Partner
                                  Hikari Tsushin Partners, L.P.

                              Signature: /s/ Tetsuya Yamada
                                        ----------------------------------

                              Name of Signer: Tetsuya Yamada
                                             -----------------------------

                              Title: Director of Domestic
                                     Investment Division
                                    --------------------------------------
<PAGE>   50
                              "HOLDERS"

                              Name: Nicholas C. Stevenson
                                   ---------------------------------------

                              Signature: /s/ Nicholas S. Stevenson
                                        ----------------------------------

                              Title: Partner
                                    --------------------------------------
<PAGE>   51
                              "HOLDERS"

                              Name: Beijing Technology Development
                                    Fund (Cayman) LDC
                                   ---------------------------------------

                              Signature: /s/ unreadable
                                        ----------------------------------

                              Title: Chairman
                                    --------------------------------------

                              Name: International Network Capital
                                    Corp. & LDC
                                   ---------------------------------------

                              Signature: /s/ unreadable
                                        ----------------------------------

                              Title: Chairman
                                    --------------------------------------

                              Name: WIH LTS Investment Ltd.
                                   ---------------------------------------

                              Signature: /s/ unreadable
                                        ----------------------------------

                              Title: Chairman
                                    --------------------------------------
<PAGE>   52
                              "HOLDERS"

                              Name: Tailwind Capital Partners, L.P.

                              By: Thomas Weisel Capital Partners LLC
                                  General Partner
                                  ----------------------------------------

                              Signature: /s/ David Baylor
                                        ----------------------------------

                              Name of Signer: David Baylor
                                             -----------------------------

                              Title: General Counsel
                                    --------------------------------------
<PAGE>   53
                              "HOLDERS"

                              Name: TSS Investment Associates, LLC
                                   ---------------------------------------

                              Signature: /s/ Donald E. Franklin
                                        ----------------------------------

                              Name of Signer: Donald E. Franklin
                                             -----------------------------

                              Title: Managing Partner
                                    --------------------------------------
<PAGE>   54
                              "HOLDERS"

                              Name: Imperial Ventures, Inc.
                                   ---------------------------------------

                              Signature: /s/ James B. Rutter
                                        ----------------------------------

                              Name of Signer: James B. Rutter
                                             -----------------------------

                              Title: President
                                    --------------------------------------
<PAGE>   55
                              "HOLDERS"

                              Name: BT Investment Partners, Inc.
                                   ---------------------------------------

                              Signature: /s/ Kristine Cicardo
                                        ----------------------------------

                              Name of Signer: Kristine Cicardo
                                             -----------------------------

                              Title: Vice President
                                    --------------------------------------
<PAGE>   56
                              "HOLDERS"

                              Name: USB Capital II, LLC
                                   ---------------------------------------

                              Signature: /s/ Charles W. Moore
                                        ----------------------------------

                              Name of Signer: Charles W. Moore
                                             -----------------------------

                              Title: Principal
                                    --------------------------------------

                              By: /s/ Justin S. Marcarone
                                  ----------------------------------------

                              Name: Justin S. Marcarone
                                   ---------------------------------------

                              Title: Partner
                                    --------------------------------------
<PAGE>   57
                              "HOLDERS"

                              Name: Lighthouse Capital Partners III, L.P.

                              By: Lighthouse Management Partners III, LLC,
                                  Its General Partner
                                  ----------------------------------------

                              Signature: /s/ Richard D. Stubblefield
                                        ----------------------------------

                              Name of Signer: Richard D. Stubblefield
                                             -----------------------------

                              Title: Managing Member
                                    --------------------------------------
<PAGE>   58
                              "HOLDERS"

                              Name: Blake Warner
                                   ---------------------------------------

                              Signature: /s/ Blake Warner
                                        ----------------------------------

                              Title:
                                    --------------------------------------
<PAGE>   59
                              "HOLDERS"

                              Name: TeleSoft Partners IA, L.P.

                              By: TeleSoft IA-GP, Inc.
                                  Its General Partner
                                  ----------------------------------------

                              Signature: /s/ Arjun Gupta
                                        ----------------------------------

                              Name of Signer: Arjun Gupta
                                             -----------------------------

                              Title: President
                                    --------------------------------------

                              TeleSoft Strategic Side Fund I, L.L.C.

                              By: TeleSoft Management, L.L.C.
                                  Its Manager
                                  ----------------------------------------

                              By: /s/ Arjun Gupta
                                 -----------------------------------------
                                 Arjun Gupta, Executive Manager
<PAGE>   60
                              "HOLDERS"

                              BRAD PERRY CAPITAL, L.P.

                              Signature: /s/ Brad Perry
                                        ----------------------------------

                              Title: General Partner
                                    --------------------------------------

                              BRAD PERRY INTERNATIONAL

                              Signature: /s/ Brad Perry
                                        ----------------------------------

                              Title: Advisor
                                    --------------------------------------

                              BRAD PERRY CAPITAL VENTURES, L.P.

                              Signature: /s/ Brad Perry
                                        ----------------------------------

                              Title: General Partner
                                    --------------------------------------

                              BRAD PERRY CAPITAL, INC.

                              Signature: /s/ Brad Perry
                                        ----------------------------------

                              Title: Chairman
                                    --------------------------------------

<PAGE>   61
                              "HOLDERS"

                              Name: William S. Slattery
                                   ---------------------------------------

                              Signature: /s/ William S. Slattery
                                        ----------------------------------

                              Title:
                                    --------------------------------------
<PAGE>   62
                              "HOLDERS"

                              Name: Alexander D. Phillips
                                   ---------------------------------------

                              Signature: /s/ Alexander D. Phillips
                                        ----------------------------------

                              Title:
                                    --------------------------------------
<PAGE>   63
                              "HOLDERS"

                              Name: Michael Dorf
                                   ---------------------------------------

                              Signature: /s/ Michael Dorf
                                        ----------------------------------

                              Title:
                                    --------------------------------------
<PAGE>   64
                              "HOLDERS"

                              Name: NEXTLINK Communications, Inc.
                                   ---------------------------------------

                              Signature: /s/ unreadable
                                        ----------------------------------

                              Title: Vice Chairman - Strategic Development
                                    --------------------------------------
<PAGE>   65
                              "HOLDERS"

                              Name: Nortel Networks Inc.
                                   ---------------------------------------

                              Signature: /s/ James Bartoszewicz
                                        ----------------------------------

                              Name of Signer: James Bartoszewicz
                                             -----------------------------

                              Title: Vice-President
                                    --------------------------------------

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