<PAGE>

                                                                    EXHIBIT 4.03

     THIS SECURITY IS A GLOBAL SECURITY WITHIN THE MEANING OF THE INDENTURE
HEREINAFTER REFERRED TO AND IS REGISTERED IN THE NAME OF THE DEPOSITARY OR A
NOMINEE OF THE DEPOSITARY, WHICH MAY BE TREATED BY THE COMPANY, THE TRUSTEE AND
ANY AGENT THEREOF AS OWNER AND HOLDER OF THIS SECURITY FOR ALL PURPOSES.

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

     UNLESS AND UNTIL IT IS EXCHANGED IN WHOLE OR IN PART FOR SECURITIES IN
DEFINITIVE REGISTERED FORM IN THE LIMITED CIRCUMSTANCES REFERRED TO IN THE
INDENTURE, THIS GLOBAL SECURITY MAY NOT BE TRANSFERRED EXCEPT AS A WHOLE BY THE
DEPOSITARY TO A NOMINEE OF THE DEPOSITARY OR BY A NOMINEE OF THE DEPOSITARY TO
THE DEPOSITARY OR ANOTHER NOMINEE OF THE DEPOSITARY OR BY THE DEPOSITARY OR ANY
SUCH NOMINEE TO A SUCCESSOR DEPOSITARY OR A NOMINEE OF SUCH SUCCESSOR
DEPOSITARY.
<PAGE>

                          EXODUS COMMUNICATIONS, INC.

           5 1/4% CONVERTIBLE SUBORDINATED NOTE DUE FEBRUARY 15, 2008

     No.   R-_                                                       $__________

     CUSIP NO. 302 088 AP 4

     EXODUS COMMUNICATIONS, INC., a corporation duly organized and existing
under the laws of the State of Delaware (herein called the "Company", which term
includes any successor Person under the Indenture referred to on the reverse
hereof), for value received, hereby promises to pay to Cede & Co., or registered
assigns, the principal sum of __________________________________ Dollars
($__________) which principal amount may from time to time be increased or
decreased to such other principal amounts (which, taken together with the
principal amounts of all other Outstanding Securities, shall not exceed
$575,000,000 in the aggregate at any time) by adjustments made on the records of
the Trustee hereinafter referred to in accordance with the Indenture) on
February 15, 2008 and to pay interest thereon, from February 9, 2001, or from
the most recent Interest Payment Date (as defined below) to which interest has
been paid or duly provided for, semi-annually in arrears on February 15 and
August 15 in each year (each, an "Interest Payment Date"), commencing August 15,
2001, at the rate of 5 1/4% per annum, using a 360-day year composed of twelve
30 day months, until the principal hereof is due, and at the rate of 7 1/4% per
annum, using a 360-day year composed of twelve 30 day months, on any overdue
principal and premium, if any, and, to the extent permitted by law, on any
overdue interest.  The interest so payable, and punctually paid or duly provided
for, on any Interest Payment Date will, as provided in the Indenture, be paid to
the Person in whose name this Security (or one or more Predecessor Subordinated
Securities) is registered at the close of business on the Record Date for such
Interest Payment Date, which shall be the February 1 or August 1 (whether or not
a Business Day), as the case may be, next preceding such Interest Payment Date.
Except as otherwise provided in the Indenture, any such interest not so
punctually paid or duly provided for will forthwith cease to be payable to the
Holder on such Record Date and may either be paid to the Person in whose name
this Security (or one or more Predecessor Subordinated Securities) is registered
at the close of business on a Special Record Date for the payment of such
Defaulted Interest to be fixed by the Trustee, notice whereof shall be given to
Holders of Securities not less than 10 days prior to the Special Record Date, or
be paid at any time in any other lawful manner not inconsistent with the
requirements of any automated quotation system or securities exchange on which
the Securities may be quoted or listed, and upon such notice as may be required
by such exchange, all as more fully provided in the Indenture.  Payments of
principal shall be made upon the surrender of this Security at the option of the
Holder at the Corporate Trust Office of the Trustee, or at such other office or
agency of the Company as may be designated by it for such purpose in the Borough
of Manhattan, The City of New York, in such coin or currency of the United
States of America as at the time of payment shall be legal tender for the
payment of public and private debts, or at such other offices or agencies as the
Company may designate, by United States Dollar check drawn
<PAGE>

on, or transfer to, a United States Dollar account (such a transfer to be made
only to a Holder of an aggregate principal amount of Securities in excess of
$2,000,000, and only if such Holder shall have furnished wire instructions in
writing to the Trustee no later than 15 days prior to the relevant payment
date). Payment of interest on this Security may be made by United States Dollar
check mailed to the address of the Person entitled thereto as such address shall
appear in the Register, or, upon written application by the Holder to the
Registrar setting forth wire instructions not later than the relevant Record
Date, by transfer to a United States Dollar account (such a transfer to be made
only to a Holder of an aggregate principal amount of Securities in excess of
$2,000,000 and only if such Holder shall have furnished wire instructions in
writing to the Trustee no later than 15 days prior to the relevant payment
date).

     Except as specifically provided herein and in the Indenture, the Company
shall not be required to make any payment with respect to any tax, assessment or
other governmental charge imposed by any government or any political subdivision
or taxing authority thereof or therein.

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

     Unless the certificate of authentication hereon has been executed by the
Trustee referred to on the reverse hereof or an Authenticating Agent by the
manual signature of one of their respective authorized signatories, this
Security shall not be entitled to any benefit under the Indenture or be valid or
obligatory for any purpose.
<PAGE>

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


                                    EXODUS COMMUNICATIONS, INC.


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

                                    Attest:
                                            ------------------------------
                                    Name:
                                    Title:



CERTIFICATE OF AUTHENTICATION

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

Dated:  ______________________, 2001


HSBC BANK USA,

as Trustee


By:
    ------------------------------------
Authorized Signatory
<PAGE>

                              REVERSE OF SECURITY

     This Security is one of a duly authorized issue of securities of the
Company designated as its "5 1/4% Convertible Subordinated Notes due February
15, 2008" (herein called the "Securities"), limited in aggregate principal
amount to $575,000,000, issued and to be issued in one or more series under a
Subordinated Indenture, dated as of February 9, 2001 as supplemented by the
Supplemental Subordinated Indenture, dated as of February 9, 2001 (herein called
the "Indenture"), between the Company and HSBC Bank USA, as Trustee (herein
called the "Trustee", which term includes any successor trustee under the
Indenture), to which Indenture and all subordinated indentures supplemental
thereto reference is hereby made for a statement of the respective rights,
limitations of rights, duties and immunities thereunder of the Company, the
Trustee, the holders of Senior Indebtedness and the Holders of the Securities
and of the terms upon which the Securities are, and are to be, authenticated and
delivered.  As provided in the Indenture and subject to certain limitations
therein set forth, Securities are exchangeable for a like aggregate principal
amount of Securities of any authorized denominations as requested by the Holder
surrendering the same upon surrender of the Security or Securities to be
exchanged, at the Corporate Trust Office of the Trustee.  The Trustee upon such
surrender by the Holder will issue the new Securities in the requested
denominations.

     No sinking fund is provided for the Securities.  The Securities will not be
subject to redemption prior to February 20, 2004 and will be redeemable on and
after that date at the option of the Company, in whole or in part, upon not less
than 30 nor more than 60 days notice to the Holders prior to the Redemption Date
at the Redemption Prices (expressed as percentages of the principal amount) set
forth below.

     The following table sets forth the Redemption Prices (expressed as
percentages of the principal amount) if this Security is redeemed during the 12-
month periods beginning on February 15 of the years indicated below (other than
2004, which period will be from February 20, 2004 to February 14, 2005);

         YEAR                               REDEMPTION PRICE
         ----                               ----------------
         2004                                   103.00%
         2005                                   102.25%
         2006                                   101.50%
         2007                                   100.75%

and thereafter at a Redemption Price equal to 100% of the principal amount,
together, in each case, with accrued interest to the Redemption Date; provided,
however, that interest installments on Securities whose Stated Maturity is on or
prior to such Redemption Date will be payable to the Holders of such Securities,
or one or more Predecessor Subordinated Securities, of record at the close of
business on the relevant Record Dates referred to on the face hereof, all as
provided in the Indenture.

     In the event of a redemption of the Securities, the Company will not be
required (a) to register the transfer or exchange of Securities for a period of
15 days immediately preceding the
<PAGE>

date notice is given identifying the serial numbers of the Securities called for
such redemption or (b) to register the transfer or exchange of any Security, or
portion thereof, called for redemption.

     In any case where the due date for the payment of the principal of,
premium, if any, or interest, on any Security or the last day on which a Holder
of a Security has a right to convert its Security shall be, at any Place of
Payment or Place of Conversion as the case may be, a day on which banks and
trust companies at such Place of Payment or Place of Conversion are authorized
or obligated by law, regulation or executive order to close, then payment of
principal, premium, if any, or interest, or delivery for conversion of such
Security need not be made on or by such date at such place but may be made on or
by the next succeeding day at such place which is not a day on which banks and
trust companies are authorized or obligated by law, regulation or executive
order to close, with the same force and effect as if made on the date for such
payment or the date fixed for redemption or repurchase, or by such last day for
conversion, and no interest shall accrue on the amount so payable for the period
after such date.

     Subject to and upon compliance with the provisions of the Indenture, the
Holder of this Security is entitled, at its option, at any time following the
initial issuance date of the Securities and on or before the close of business
on the date of Maturity, or in case this Security or a portion hereof is called
for redemption or the Holder hereof has exercised its right to require the
Company to repurchase this Security or such portion hereof, then in respect of
this Security until and including, but (unless the Company defaults in making
the payment due upon redemption or repurchase, as the case may be) not after,
the close of business on the Redemption Date or the Repurchase Date, as the case
may be, to convert this Security (or any portion of the principal amount hereof
that is an integral multiple of $1,000, provided that the unconverted portion of
such principal amount is $1,000 or any integral multiple of $1,000 in excess
thereof) into fully paid and nonassessable shares of Common Stock of the Company
at an initial Conversion Rate of 43.9464 shares of Common Stock for each $1,000
principal amount of Securities (or at the current adjusted Conversion Rate if an
adjustment has been made as provided in the Indenture) by surrender of this
Security, duly endorsed or assigned to the Company or in blank, with the
conversion notice hereon duly executed and, in case such surrender shall be made
during the period from the close of business on any Record Date next preceding
any Interest Payment Date to the opening of business on such Interest Payment
Date (except if this Security or portion thereof has been called for redemption
on a Redemption Date during the period from such Record Date through the date
that is three (3) Business Days following such Interest Payment Date), also
accompanied by payment in New York Clearing House or other funds acceptable to
the Company of an amount equal to the interest payable on such Interest Payment
Date on the principal amount of this Security then being converted, to the
Company at the Corporate Trust Office of the Trustee, or at such other office or
agency of the Company, subject to any laws or regulations applicable thereto and
subject to the right of the Company to terminate the appointment of any
Conversion Agent (as defined below) as may be designated by it for such purpose
in the Borough of  Manhattan, The City of New York, or at such other offices or
agencies as the Company may designate (each a "Conversion Agent").  Subject, in
the case of a conversion after the close of business on the Record Date next
preceding any Interest Payment Date and on or before the close of business on
such Interest Payment Date, to the right of the Holder of this Security (or any
Predecessor Subordinated Security of record as of such Record Date) to receive
the related installment of interest to the extent and under the circumstances
<PAGE>

provided in the Indenture, no cash payment or adjustment is to be made on
conversion for interest accrued hereon from the Interest Payment Date next
preceding the day of conversion, or for dividends on the Common Stock issued on
conversion hereof.  The Company shall thereafter deliver to the Holder the fixed
number of shares of Common Stock (together with any cash adjustment, as provided
in the Indenture) into which this Security is convertible and such delivery will
be deemed to satisfy the Company's obligation to pay the principal amount of
this Security.  No fractions of shares or scrip representing fractions of shares
will be issued on conversion, but instead of any fractional interest (calculated
to the nearest 1/100th of a share) the Company shall pay a cash adjustment as
provided in the Indenture.  The Conversion Rate is subject to adjustment as
provided in the Indenture.  In addition, the Indenture provides that in case of
certain consolidations or mergers to which the Company is a party (other than a
consolidation or merger that does not result in any reclassification,
conversion, exchange or cancellation of the Common Stock) or the conveyance,
transfer, sale or lease of all or substantially all of the property and assets
of the Company, the Indenture shall be amended, without the consent of any
Holders of Securities, so that this Security, if then Outstanding, will be
convertible thereafter, during the period this Security shall be convertible as
specified above, only into the kind and amount of securities, cash and other
property receivable upon such consolidation, merger, conveyance, transfer, sale
or lease by a holder of the number of  shares of Common Stock of the Company
into which this Security could have been converted immediately prior to such
consolidation, merger, conveyance, transfer, sale or lease (assuming such holder
of Common Stock is not a Constituent Person or an Affiliate of a Constituent
Person, failed to exercise any rights of election and received per share the
kind and amount received per share by a plurality of Non-electing Shares).  No
adjustment in the Conversion Rate will be made until such adjustment would
require an increase or decrease of at least one percent of such rate, provided
that any adjustment that would otherwise be made will be carried forward and
taken into account in the computation of any subsequent adjustment.

     If a Change in Control occurs, the Holder of this Security, at the Holder's
option, shall have the right, in accordance with the provisions of the
Indenture, to require the Company to repurchase this Security (or any portion of
the principal amount hereof that is an integral multiple of $1,000) for cash at
a Repurchase Price equal to 100% of the principal amount thereof plus interest
accrued to the Repurchase Date.  At the option of the Company, the Repurchase
Price may be paid in cash or, subject to the conditions provided in the
Indenture, by delivery of shares of Common Stock having a fair market value
equal to the Repurchase Price.  For purposes of this paragraph, the fair market
value of shares of Common Stock shall be determined by the Company and shall be
equal to 95% of the average of the Closing Prices Per Share for the five
consecutive Trading Days immediately preceding and including the third Trading
Day prior to the Repurchase Date.  Whenever in this Security there is a
reference, in any context, to the principal of any Security as of any time, such
reference shall be deemed to include reference to the Repurchase Price payable
in respect of such Security to the extent that such Repurchase Price is, was or
would be so payable at such time, and express mention of the Repurchase Price in
any provision of this Security shall not be construed as excluding the
Repurchase Price so payable in those provisions of this Security when such
express mention is not made; provided, however, that, for the purposes of the
third succeeding paragraph, such reference shall be deemed to include reference
to the Repurchase Price only to the extent the Repurchase Price is payable in
cash.
<PAGE>

     In the event of a deposit or withdrawal of an interest in this Security,
including an exchange, transfer, redemption, repurchase or conversion of this
Security in part only, the Trustee, as custodian of the Depositary, shall make
an adjustment on its records to reflect such deposit or withdrawal in accordance
with the Applicable Procedures.

     The indebtedness evidenced by this Security is, to the extent and in the
manner provided in the Indenture, subordinate and subject in right of payment to
the prior payment in full of all Senior Indebtedness of the Company, and this
Security is issued subject to such provisions of the Indenture with respect
thereto.  Each Holder of this Security, by accepting the same, (a) agrees to and
shall be bound by such provisions, (b) authorizes and directs the Trustee on his
behalf to take such action as may be necessary or appropriate to effectuate the
subordination so provided and (c) appoints the Trustee his attorney-in-fact for
any and all such purposes.

     If an Event of Default shall occur and be continuing, the principal of all
the Securities, together with accrued interest to the date of declaration, may
be declared due and payable in the manner and with the effect provided in the
Indenture.  Upon payment (i) of the amount of principal so declared due and
payable, together with accrued interest to the date of declaration, and (ii) of
interest on any overdue principal and, to the extent permitted by applicable
law, overdue interest, all of the Company's obligations in respect of the
payment of the principal of and interest on the Securities shall terminate.

     The Indenture permits, with certain exceptions as therein provided, the
amendment thereof and the modification of the rights and obligations of the
Company and the rights of the Holders of the Securities under the Indenture at
any time by the Company and the Trustee with either (a) the written consent of
the Holders of not less than a majority in principal amount of the Securities at
the time Outstanding, or (b) by the adoption of a resolution, at a meeting of
Holders of the Outstanding Securities at which a quorum is present, by the
Holders of at least 66-2/3% in aggregate principal amount of the Outstanding
Securities represented and entitled to vote at such meeting.  The Indenture also
contains provisions permitting the Holders of specified percentages in principal
amount of the Securities at the time Outstanding, on behalf of the Holders of
all the Securities, to waive compliance by the Company with certain provisions
of the Indenture and certain past defaults under the Indenture and their
consequences.  Any such consent or waiver by the Holder of this Security shall
be conclusive and binding upon such Holder and upon all future Holders of this
Security and of any Security issued in exchange therefore or in lieu hereof,
whether or not notation of such consent or waiver is made upon this Security or
such other Security.

     As provided in and subject to the provisions of the Indenture, the Holder
of this Security shall not have the right to institute any proceeding with
respect to the Indenture or for the appointment of a receiver or trustee or for
any other remedy thereunder, unless such Holder shall have previously given the
Trustee written notice of a continuing Event of Default, the Holders of not less
than 25% in principal amount of the Outstanding Securities shall have made
written request to the Trustee to institute proceedings in respect of such Event
of Default as Trustee and offered the Trustee reasonable indemnity against the
costs, expenses and liabilities to be incurred in compliance with such request
(including the reasonable fees of counsel for the Trustee) and the Trustee shall
not have received from the Holders of a majority in principal amount of the
<PAGE>

Securities Outstanding a direction inconsistent with such request, and shall
have failed to institute any such proceeding, for 60 days after receipt of such
notice, request and offer of indemnity.  The foregoing shall not apply to any
suit instituted by the Holder of this Security for the enforcement of any
payment of principal hereof, premiums if any, or interest hereon on or after the
respective due dates expressed herein or for the enforcement of the right to
convert this Security as provided in the Indenture.

     No reference herein to the Indenture and no provision of this Security or
of the Indenture shall alter or impair the obligation of the Company, which is
absolute and unconditional, to pay the principal of, premium, if any, and
interest on this Security at the times, places and rate, and in the coin or
currency, herein prescribed or to convert this Security as provided in the
Indenture.

     As provided in the Indenture and subject to certain limitations therein set
forth, the transfer of this Security is registrable on the Register upon
surrender of this Security for registration of transfer at the Corporate Trust
Office of the Trustee or at such other office or agency of the Company as may be
designated by it for such purpose in the Borough of Manhattan, The City of New
York (which shall initially be the Corporate Trust Office of the Trustee), or at
such other offices or agencies as the Company may designate, duly endorsed by,
or accompanied by a written instrument of transfer in form satisfactory to the
Company and the Registrar duly executed by, the Holder thereof or his attorney
duly authorized in writing, and thereupon one or more new Securities, of
authorized denominations and for the same aggregate principal amount, will be
issued to the designated transferee or transferees by the Registrar.  No service
charge shall be made for any such registration of transfer or exchange, but the
Company may require payment of a sum sufficient to recover any tax or other
governmental charge payable in connection therewith.

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

     No recourse for the payment of the principal (and premium, if any) or
interest on this Security and no recourse under or upon any obligation, covenant
or agreement of the Company in the Indenture or any subordinated indenture
supplemental thereto or in any Security, or because of the creation of any
indebtedness represented thereby, shall be had against any incorporator,
stockholder, employee, agent, officer or director or subsidiary, as such, past,
present or future, of the Company or of any successor corporation, either
directly or through the Company or any successor corporation, whether by virtue
of any constitution, statute or rule of law or by the enforcement of any
assessment or penalty or otherwise, all such liability being, by the acceptance
hereof and as part of consideration for the issue hereof, expressly waived and
released.

     THE INDENTURE AND THIS SECURITY SHALL BE GOVERNED BY AND CONSTRUED IN
ACCORDANCE WITH THE LAWS OF THE STATE OF NEW
<PAGE>

YORK, UNITED STATES OF AMERICA, WITHOUT REGARD TO THE PRINCIPLES OF CONFLICTS OF
LAWS.

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

                                 ABBREVIATIONS

     The following abbreviations, when used in the inscription of the face of
this Security, shall be construed as though they were written out in full
according to applicable laws or regulations:
                                       UNIF GIFT MIN ACT   ____ Custodian _____
TEN COM   as tenant in common                             (Cust)         (Minor)
TEN ENT   as tenants by the                               under Uniform Gifts
          entireties (Cust)                               to Minors Act _____
JT TEN    as joint tenants with                                        (State)
          right of survivorship and
          not as tenants in
          common

     Additional abbreviations may also be used though not in the above list.
<PAGE>

                    ELECTION OF HOLDER TO REQUIRE REPURCHASE

                (i)  Pursuant to Article X of the Supplemental Indenture, the
undersigned hereby elects to have this Security repurchased by the Company.

                (ii) The undersigned hereby directs the Company to pay it or
______________ an amount in cash or, at the Company's election, Common Stock
valued as set forth in the Indenture, equal to 100% of the principal amount to
be repurchased (as set forth below), plus interest accrued to the Repurchase
Date, as provided in the Indenture.

Dated:

Signature(s)

Signature(s) must be guaranteed by an Eligible
Guarantor Institution with membership in an
approved signature guarantee program pursuant
to Rule 17Ad-15 under the Securities Exchange
Act of 1934.

Signature Guaranteed

Principal amount to be repurchased (at least
$5,000 or an integral multiple of $1,000
in excess thereof):  ___________________

Remaining principal amount following such
repurchase (not less than $1,000):
______________

NOTICE:  The signature to the foregoing Election must correspond to the Name as
written upon the face of this Security in every particular, without alteration
or any change whatsoever.