EXHIBIT 10.06
                                                                   -------------


                           SECOND AMENDMENT AGREEMENT
                           --------------------------

         SECOND AMENDMENT AGREEMENT (this "AMENDMENT AGREEMENT") dated as of
July 21, 2000 by and between DSL.net, Inc. (the "BORROWER") and Fleet National
Bank (the "BANK"), amending a certain Credit Agreement by and between the
Borrower and the Bank dated as of May 12, 1999, as amended by that Amendment and
Waiver Agreement dated as of June 12, 2000 (as amended, the "CREDIT AGREEMENT").

                               W I T N E S S E T H
                               -------------------

         WHEREAS, pursuant to the terms of the Credit Agreement, the Bank has
made loans to the Borrower; and

         WHEREAS, the Borrower has requested that the Bank amend the Credit
Agreement; and

         WHEREAS, the Bank is willing to amend certain terms and conditions of
the Credit Agreement on the terms and conditions set forth herein.

         NOW, THEREFORE, for good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the parties hereto agree as
follows:

         SS.1. DEFINITIONS. Capitalized terms used herein without definition
that are defined in the Credit Agreement shall have the same meanings herein as
therein.

         SS.2. RATIFICATION OF EXISTING AGREEMENTS. All of the Borrower's
obligations and liabilities to the Bank as evidenced by or otherwise arising
under the Credit Agreement, the Note and the other Loan Documents, except as
otherwise expressly modified in this Amendment Agreement upon the terms set
forth herein, are, by the Borrower's execution of this Amendment Agreement,
ratified and confirmed in all respects. In addition, by the Borrower's execution
of this Amendment Agreement, the Borrower represents and warrants that no
counterclaim, right of set-off or defense of any kind exists or is outstanding
with respect to such obligations and liabilities.

         SS.3. REPRESENTATIONS AND WARRANTIES. All of the representations and
warranties made by the Borrower in the Credit Agreement, the Note and the other
Loan Documents are true and correct on the date hereof as if made on and as of
the date hereof, except to the extent that (i) such representations are updated
as set forth on Schedule A attached hereto or (ii) any of such representations
and warranties expressly relate by their terms to a prior date and for matters
previously disclosed to the Bank in writing.


<PAGE>

                                      -2-


         SS.4. CONDITIONS PRECEDENT. The effectiveness of the amendments
contemplated hereby shall be subject to the satisfaction on or before the date
hereof of each of the following conditions precedent:

                  (a) Representations and Warranties. All of the representations
         and warranties made by the Borrower herein, whether directly or
         incorporated by reference, shall be true and correct on the date
         hereof, except as provided in ss.3 hereof.

                  (b) Performance; No Event of Default. The Borrower shall have
         performed and complied in all material respects with all terms and
         conditions herein required to be performed or complied with by it prior
         to or at the time hereof, and there shall exist no Event of Default or
         condition which, with either or both the giving of notice of the lapse
         of time, would result in an Event of Default upon the execution and
         delivery of this Amendment Agreement.

                  (c) Corporate Action. All requisite corporate action necessary
         for the valid execution, delivery and performance by the Borrower of
         this Amendment Agreement and all other instruments and documents
         delivered by the Borrower in connection therewith shall have been duly
         and effectively taken.

                  (d) Delivery. The parties hereto shall have executed and
         delivered this Amendment Agreement, in form and substance satisfactory
         to the Bank.

                  (e) Fees and Expenses. The Borrower shall have paid to the
         Bank all reasonable fees and expenses incurred by the Bank in
         connection with this Amendment Agreement, the Credit Agreement and the
         other Loan Documents.

         SS.5.    AMENDMENTS TO THE CREDIT AGREEMENT.

                  5.1. AMENDMENT TOSS.7.2(A). Section 7.2(a) of the Credit
Agreement is hereby amended in its entirety to read as follows:

                           "(a) create, incur or assume any Indebtedness other
         than (i) Indebtedness to the Bank, (ii) Indebtedness in respect of the
         acquisition of property or under any Capital Lease Obligation (other
         than the amounts permitted under subsection (iii) hereof) which does
         not exceed the sum of $5,000,000 in the aggregate, (iii) Indebtedness
         not exceeding the sum of $10,000,000 under that certain Capital Lease
         Obligation as to which Copper Mountain Networks, Inc. ("Copper
         Mountain") is the lender and provider of such funding, (iv) current
         liabilities of the Borrower or any of its Subsidiaries not incurred
         through the borrowing of money or the obtaining of credit except credit
         on an open account customarily extended, (v) Indebtedness in respect


<PAGE>

                                      -3-

         of taxes or other governmental charges contested in good faith and by
         appropriate proceedings and for which adequate reserves have been
         taken, and (vi) Indebtedness not included above and listed on Schedule
         7.2(a) hereto;"

                  5.2. AMENDMENT TOSS.7.2(B)(IV). Section 7.2(b)(iv) of the
Credit Agreement is hereby amended by inserting the phrase
"and/orss.7.2(a)(iii)" after "ss.7.2(a)(ii)" into the third to last line
ofss.7.2(b).

                  5.3. AMENDMENT TOSS.7.2(E). Section 7.2(e) of the Credit
Agreement is hereby amended by inserting the following at the beginning of such
subsection to read as follows:

                  "except for that certain sale-leaseback transaction by the
         Borrower with Copper Mountain with respect to certain assets previously
         sold by Copper Mountain to the Borrower during the period beginning on
         April 30, 2000 through and including July 31, 2000 having an aggregate
         purchase price not to exceed $3,041,316.85,"

         SS.6. ADDITIONAL COVENANTS. Without any prejudice or impairment
whatsoever to any of the Bank's rights and remedies contained in the Credit
Agreement and the covenants contained therein, the Note or in any of the other
Loan Documents, the Borrower additionally covenants and agrees with the Bank as
follows:

                  (a) On or before August 20, 2000, the Borrower shall pay in
         full all of the remaining fees and expenses due and owing under the
         June Bill.

                  (b) The Borrower shall comply and continue to comply with all
         of the terms, covenants and provisions contained in the Credit
         Agreement, the Note and the other Loan Documents, except as such terms,
         covenants and provisions are expressly modified by this Amendment
         Agreement upon the terms set forth herein.

                  (c) The Borrower will provide to the Bank such financial
         information as the Bank may reasonably request from time to time and at
         the Borrower's expense.

                  (d) The Borrower shall at any time or from time to time
         execute and deliver such further instruments, and take such further
         action as the Bank may reasonably request, in each case further to
         effect the purposes of this Amendment Agreement, the Credit Agreement,
         the Note and the other Loan Documents.

         The Borrower expressly acknowledges and agrees that any failure by the
Borrower to comply with the terms and conditions of this ss.6 or any other
provisions


<PAGE>

                                      -4-

contained in this Amendment Agreement shall constitute an Event of Default under
the Credit Agreement.

         SS.7. EXPENSES. The Borrower agrees to pay to the Bank upon demand (a)
an amount equal to any and all out-of-pocket costs or expenses (including
reasonable legal fees and disbursements and appraisal expenses) incurred or
sustained by the Bank in connection with the preparation of this Amendment
Agreement and related matters, including without limitation, any reasonable
legal fees in connection with any proposed amendments or financing arrangements
between the Borrower and the Bank and (b) from time to time any and all
out-of-pocket costs or expenses (including reasonable legal fees and
disbursements) hereafter incurred or sustained by the Bank in connection with
the administration of credit extended by the Bank to the Borrower or the
preservation of or enforcement of the Bank's rights under the Credit Agreement,
the Note or the other Loan Documents or in respect of any of the Borrower's
other obligations to the Bank.

         SS.8.      MISCELLANEOUS.

                  (a) This Amendment Agreement shall be governed by and
         construed in accordance with the laws of the Commonwealth of
         Massachusetts.

                  (b) Except as otherwise expressly provided by this Amendment
         Agreement, all of the respective terms, conditions and provisions of
         the Credit Agreement shall remain the same. It is declared and agreed
         by each of the parties hereto that the Credit Agreement, as amended
         hereby, shall continue in full force and effect, and that this
         Amendment Agreement and the Credit Agreement be read and construed as
         one instrument, and all references in the Loan Documents to the Credit
         Agreement shall hereafter refer to the Credit Agreement, as amended by
         this Amendment Agreement


<PAGE>

                                      -5-

         IN WITNESS WHEREOF, each of the parties hereto have caused this
Agreement to be executed in its name and behalf by its duly authorized officer
as an instrument under seal as of the date first written above.

                                      FLEET NATIONAL BANK


                                      By: /s/ Suzanne M. McKay
                                         ---------------------------------
                                         Its: Vice President

                                      DSL.NET, INC.


                                      By: /s/ S. Zamansky
                                         ---------------------------------
                                         Its: Vice President