<PAGE>

                      CONFIDENTIAL ANTI-DILUTION AGREEMENT

         This Agreement is made this 30th day of November, 1999, by and
between Rackspace, Ltd., a Texas limited partnership, Macroweb, LC, its
general partner, Trout, Ltd., a Texas limited partnership ("Trout"), Weston
Investment Interests, LC, a Nevada limited liability company ("Weston"),
MiniPat & Company, Ltd. ("MiniPat"), Patrick R. Condon ("Condon"), Richard
Yoo ("Yoo") and Dirk Elmendorf ("Elmendorf") and First Inning Investors, L.P.
("First Inning"), Isom Capital Partners I, L.P.("Isom") and Hamilton
Companies, LLC ("Hamilton").

         This Agreement, which provides Weston, First Inning, Isom, Hamilton,
MiniPat and Trout (collectively, the "Second Amendment Investors") limited
protections against dilution with respect to the Units in the Partnership
purchased by them under the terms of the Second Amendment to Agreement of
Limited Partnership of Rackspace, Ltd, is made by the parties hereto to
induce the Second Amendment Investors to purchase Units in the Partnership.

         THE PARTIES AGREE AS FOLLOWS:

         1. TERM. This agreement applies to any equity investment made in the
Partnership between the date hereof and August 30, 2000, provided that this
agreement shall terminate prior to August 30, 2000 upon the closing of an
offering of equity in the Partnership whereby more than $1,500,000.00 in
cash is raised provided that the purchase price per Unit is not less than
$2.10, adjusted by any split or reverse split in the number of Units of the
Partnership which occurs after the date hereof("as Adjusted"). The period
during which this Agreement is in effect is referred to as the "Term".

         2. ANTI-DILUTION RIGHTS. To the extent that during the Term the
Partnership issues any additional Units (the "Additional Units") (other than
an issuance pursuant to an option agreement with an employee or otherwise to
compensate an employee, or incident to an acquisition of assets by the
Partnership in which more than 700,000 Units, as Adjusted, are issued to the
seller of such assets), and the purchase price per Unit is less than $2.10
(as determined without regard to the operation of this Agreement and the
issuance of Adjusting Units), as Adjusted ("Dilutive Transaction"),
contemporaneously with the Dilutive Transaction, the Partnership will issue
the Second Amendment Investors additional Units in the Partnership in an
amount which provides them with the Ownership Percentage Interest which they
would have held in the Partnership represented by the Units purchased by them
on this date (for the purposes of calculating such Ownership Percentage
Interest, the 238,095 Units to be purchase by Hamilton under the option
contained in the Second Amendment shall be treated as if the option were
exercised on this date, but only to the extent that Hamilton exercises such
option), had the Additional Units been sold at $2.10 per Unit, as Adjusted
("Adjusting Units"). As a result of this adjustment, the new investor(s)
under the Dilutive Transaction will also receive Adjusting Units in an amount
necessary to provide him with the Ownership Percentage Interest in the
Partnership contemplated by the Dilutive Transaction. Adjusting Units shall
not be subject to any pre-emptive rights contained in the Agreement of
Limited Partnership of Rackspace, Ltd.

<PAGE>

         For example: Assume that six months after the date of this agreement
a new investor is willing to invest $2,000,000.00 in exchange for 10% of
Rackspace. Assuming there are 15 Million Units outstanding, if this agreement
were not in effect, the new investor would receive 1,666,666 units at $1.20
per unit and the aggregate units outstanding would be l6,666,666. Because the
per unit price for the new investment is less than $2.10, the proposed
investment would be a Dilutive Transaction. Had the Dilutive Transaction been
at $2.10 per unit, 952,380.95 additional units would have been issued to the
new investor ($2,000,000 divided by $2.10) and 15,952,380.95 aggregate units
would have been outstanding (15,000,000 plus 952,380.95). Assuming the Second
Amendment Investors owned 7,500,000 or 50% of the units outstanding before
the Dilutive Transaction, if the new units were sold at $2.10 per unit the
Second Amended Investors would hold 47.01492% of the outstanding units
(7,500,000 is 47.0492% of 15,952,380.95). The Second Amended Investors would
hold only 45.00l8% of the units outstanding if the Dilutive Transaction were
to occur without adjustment (7,500,000 is 45.0018% of 16,666,666).
Consequently, under the terms of this agreement the Second Amendment
Investors must receive enough Adjustment Units to own 47.01492% of the
aggregate outstanding units after the Dilutive Transaction and the
new investor must receive enough Adjustment Units after the Dilutive
Transaction to own 10% of the aggregate outstanding units after the Dilutive
Transaction. In this example since the Second Amendment Investors are
entitled to hold 47.0192% of the aggregate units and the new investor is
entitled to own 10% of the aggregate units after the Dilutive Transaction,
the holders of the 7,500,000 units not held by the Second Amendment Investors
pre Dilutive Transaction can only hold 42.98508% of the aggregate units after
the Dilutive Transaction (100% less 57.0192%). Consequently, the outstanding
units after the Dilutive Transaction must be 17,447,914 (7,500,000 is
42.98508% of 17,447,914), and 1,744,791.4 (10%) must be held by the new
investor and 8,203,122.8 (47.01492%) must be held by the Second Amended
Investors. To accomplish this the new investor must be issued 78,125.4
Adjustment Units (1,747,914 minus 1,666,666) and the Second Amended Investors
must be issued 703,122.8 Adjustment Units (8,203,122.8 minus 7,500,000).

         3. CONFIDENTIALITY. The parties to this agreement agree to keep its
terms strictly confidential and not to disclose the terms hereof to any third
party other than the equity holders of such parties without the consent of
the General Partner (or any successor entity to the Partnership); provided,
however, that this provision shall not apply to information which, at the time
of disclosure, is already part of the public domain (except by breach of this
Agreement) and information which is required to be disclosed by law.

<PAGE>

IN WITNESS WHEREOF, THE PARTIES HERETO HAVE DULY EXECUTED AND DELIVERED THIS
AGREEMENT ON THE DATE FIRST WRITTEN ABOVE.

         RACKSPACE, LTD.
                  By: Macroweb, LC, general partner

                  By: /s/ Morris Miller, member
                     ---------------------------

                  By: /s/ Graham Weston, manager
                     ---------------------------


         Macroweb, LC,

                  By: /s/ Morris Miller, member
                      ---------------------------

                  Its: member
                      ---------------------------

         Trout, Ltd.

                  Macroweb, LC, general partner

                  By: /s/ Morris Miller, member
                      ---------------------------

                  Its: member
                      ---------------------------

         MiniPat & Company, Ltd.

                  Patrick R. Condon, general partner

                  By: /s/ Patrick R. Condon
                     ---------------------------


          /s/ Patrick R. Condon
          ---------------------------
          Patrick Condon

          /s/ Richard Yoo
          ---------------------------
          Richard Yoo

          /s/ Dirk Elmendorf
          ---------------------------
          Dirk Elmendorf


<PAGE>

         First Inning Investors, L.P.


                  By: Trango Capital, L.L.C., its general partner

                           By: /s/ Quincy Lee
                              -----------------------
                           Quincy Lee, manager




         Isom Capital Partners I, L.P.


                  By: BESK Funding, Inc. its general partner

                           By: /s/ S. James Bishken
                              ---------------------------
                              S. James Bishken, President


         Hamilton Companies, LLC


         By: /s/ Frederick C. Hamilton
            --------------------------


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


         Weston Investment Interests, LC


         By: /s/ Graham Weston
             ---------------------------

         Its: manager
             ---------------------------


<PAGE>

First Inning Investors, L.P.

         By: Trango Capital, L.L.C., its general partner


                  By: /s/ Quincy Lee
                     ---------------------------
                     Quincy Lee, manager



Isom Capital Partners I, L.P.

         By: BESK Funding, Inc. its general partner


                  By: /s/ S. James Bishken
                     ---------------------------
                     S. James Bishken, President


The Hamilton Companies, LLC

By: /s/ Frederick C. Hamilton
   ---------------------------

Title: President and Manager
      ------------------------


Weston Investment Interests, LC

By: /s/ Graham Weston
    ---------------------------

Its: manager
    ---------------------------


<PAGE>

                AMENDMENT TO CONFIDENTIAL ANTI-DILUTION AGREEMENT

         This Amendment to Confidential Anti-Dilution Agreement (hereinafter
referred to as the "Amendment") is made this 22nd day of February, 2000, by
and among Rackspace, Ltd. (the "Partnership"), Macroweb, LC, a Texas limited
liability company (the "General Partner" or "Macroweb"), Trout, Ltd., a Texas
limited partnership ("Trout"), Richard Yoo ("Yoo"), Patrick Condon ("Condon")
and Dirk Elmendorf ("Elmendorf"), Isom Capital Partners I, L.P. ("Isom"),
First Inning Investors, L.P. ("First Inning"), The Hamilton Companies LLC, a
Colorado limited liability company ("Hamilton"), Weston Investment Interest,
L.L.C., a Nevada limited liability company ("Weston Entity"), MiniPat &
Company, Ltd., a Texas limited partnership ("MiniPat")(Macroweb, Trout, Yoo,
Condon, Elmendorf, Isom, First Inning, Hamilton, Weston Entity and MiniPat
are sometimes referred to herein as the "Existing Partners") and 2M
Technology Ventures, L.P. (the "New Partner" or "2M"). This Amendment amends
the Confidential Anti-Dilution Agreement dated November 30, 1999 (hereinafter
referred to as the "Agreement"). Except as amended by this Amendment, the
terms of the Agreement shall continue in full force and effect. Capitalized
terms used herein shall, unless otherwise specified, have the meanings
assigned to them in the Agreement.

         The parties to this Amendment agree that for the purposes of the
Agreement, 2M shall be included as a "Second Amendment Investor" and as such
shall have the same rights and benefits under the Agreement as those parties
who were originally named in the Agreement as Second Amendment Investors. In
addition, 2M agrees to be bound by the terms and conditions contained in the
Agreement, including but not limited to the confidentiality provisions
contained in the Agreement.

Executed as of the date first written above.

                                       RACKSPACE, LTD.

                                            By: Macroweb, LC, general partner

                                                By: /s/ Graham Weston
                                                   ---------------------------
                                                         Member

                                                By: /s/ Morris A. Miller
                                                   ---------------------------
                                                         Member

                                       Macroweb, LC

                                       /s/ Morris A. Miller
                                       ---------------------------------------
                                       Morris A. Miller, Member

                                       /s/ Graham M. Weston
                                       ---------------------------------------
                                       Graham M. Weston, Member
<PAGE>

                                    LIMITED PARTNERS:

                                    /s/ Richard Yoo
                                    -----------------------------------------
                                    Richard Yoo

                                    /s/ Dirk Elmendorf
                                    -----------------------------------------
                                    Dirk Elmendorf

                                    /s/ Patrick Condon
                                    -----------------------------------------
                                    Patrick Condon

                                    Trout, Ltd.

                                    By:  Knightsbridge, L.C.,General Partner

                                         By: /s/ Graham Weston
                                            ----------------------------------

                                         Its: manager
                                             ---------------------------------

                                    Isom Capital Partners I, L.P.

                                    By:  BESK Funding, Inc., General Partner

                                         By: /s/ S. James Bishkin
                                            ----------------------------------
                                                      S. James Bishkin
                                                      President

                                    First Inning Investors, L.P.

                                         By:  Trango Capital L.L.C., General
                                              Partner

                                              By: /s/ Quincy J. Lee
                                                 -----------------------------
                                                   Quincy J. Lee, Manager

                                    The Hamilton Companies LLC

                                    By: /s/ Frederick C. Hamilton
                                       ---------------------------------------

<PAGE>

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



                                    Weston Investment Interest, L.L.C.

                                    By: /s/ Graham Weston
                                       ---------------------------------------


                                    MiniPat & Company, Ltd.

                                    By: /s/ Patrick Condon
                                       ---------------------------------------

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

                                    2M Technology Ventures, L.P.

                                    By:  2M Technology Group, L.L.C.,
                                    Its: General Partner

                                             By: /s/ Steven D. Leeke
                                                ------------------------------