Document:

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                 ASSUMPTION, ASSIGMENT AND RESTATEMENT AGREEMENT

                                                                   Exhibit 10.55

     THIS ASSUMPTION, ASSIGNMENT AND RESTATEMENT AGREEMENT (the "AGREEMENT") is
made and entered into as of the 19th day of November, 2001, by and among (i)
Network Access Solutions Corporation, a Delaware corporation, or its permitted
designee ("NAS"), (ii) Covad Communications Company, a California corporation
("COVAD"), (iii) Ardent, Inc., a Virginia corporation, and (iv) Ardent
Communications, Inc., a Delaware corporation (together, with Ardent, Inc.,
"ARDENT," and, collectively with Covad and NAS, the "PARTIES").

     WHEREAS, Ardent is engaged in the business of supplying broadband Internet
access solutions and web services (collectively, the "BUSINESS");

     WHEREAS, on October 10, 2001 (the "PETITION DATE"), Ardent filed voluntary
chapter 11 petitions commencing cases in the United States Bankruptcy Court for
the District of Columbia (the "BANKRUPTCY COURT"), Case Nos. 01-02085 and
01-02086;

     WHEREAS, NAS and Ardent executed an Asset Purchase Agreement, dated as of
October 25, 2001, whereby NAS agreed to purchase certain of the assets of Ardent
related to or used by Ardent in connection with the Business and to assume
certain executory contracts of Ardent related to the Business (collectively, the
"ACQUIRED ASSETS") (as more particularly defined in ARTICLE 1 thereof) in
accordance with Sections 105, 363 and 365 of the Bankruptcy Code (the "PURCHASE
AGREEMENT");

     WHEREAS, pursuant to the Services Agreement, dated as of August 2, 1999
(the "SERVICES AGREEMENT"), and the ISP Customer Agreement for Telespeed
Services, dated October 29, 1998 (the "COVAD ISP AGREEMENT"), each by and
between Ardent and Covad, Covad agreed to provide digital subscriber line
("DSL") service to certain customers of Ardent (together, the "COVAD AGREEMENTS"
which term shall include all amendments made hereunder);

     WHEREAS, Ardent is currently liable to Covad for $4,878,403.12 for services
rendered under the Covad Agreements prior to the Petition Date (the
"PRE-PETITION AMOUNT"), and is currently liable for $980,962.57 for services
rendered under the Covad Agreements after the Petition Date and prior to
Closing, as defined herein (the "POST-PETITION AMOUNT");

     WHEREAS, in connection with the Purchase Agreement, Ardent wishes to assume
and assign to NAS the Covad Agreements, as modified by this Agreement, pursuant
to Section 365 of the Bankruptcy Code, and Covad will agree, and not object, to
the assumption and assignment of the Covad Agreements upon the execution of this
Agreement and related agreements;

     WHEREAS, NAS and Covad wish to restate the Covad Agreements following the
assumption and assignment of such agreements pursuant to the terms hereof; and

     WHEREAS, pursuant to the Purchase Agreement, NAS is obligated to pay to
Covad the Pre-Petition amount less $178,403.12 and Ardent is obligated to pay to
Covad $178,403.12, plus the Post-Petition Amount.

     NOW, THEREFORE, in consideration of the mutual promises, covenants and
agreements set forth in this Agreement, the sufficiency of which the Parties
acknowledge, it is agreed as follows:

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     1. CURE OF PRE-PETITION DEFAULTS

          (a) NAS hereby agrees to pay to Covad $4,700,000 in cash over time
pursuant to the terms of a secured promissory note, a form of which is attached
hereto as EXHIBIT 1 (the "Note"). Pursuant to the Note, NAS shall pay $3,000,000
in cash at closing by wire transfer. The Note and all of its terms are hereby
incorporated in this agreement as if fully set forth herein.

          (b) Ardent hereby agrees to pay to Covad $178,403.12 in cash at
closing by wire transfer.

          (c) NAS hereby agrees to provide to Covad a Letter of Credit, a form
of which is attached hereto as EXHIBIT 2 to secure performance of NAS'
obligations to Covad under this and all other agreements between NAS and Covad
(e.g. Services Agreements) through the term of all agreements.

          (d) Except as it is contemplated herein, Covad hereby covenants that
it will not seek from NAS any further compensation, payment or reimbursement of
any kind for any amounts due, liabilities, causes of action, breach of warranty,
contract payment or any other obligation of any sort under the Covad Agreements
arising prior to the Closing, as defined herein.

          (e) Covad hereby covenants that it will not object to, and will
support, Ardent's motion pursuant to Section 365 of the Bankruptcy Code to
assume the Covad Agreements and assign them to NAS. Covad further covenants that
the protections inuring to Covad under this Agreement constitute "adequate
assurance of future performance" under the Covad Agreements, as that phrase is
used in Section 365 of the Bankruptcy Code, and that the payments to be made
pursuant to this Agreement constitute the cure of all defaults as required by
Section 365. Nothing herein shall prevent Covad from entering into any
negotiations with any other prospective purchaser of the Acquired Assets
concerning the assumption and assignment of the Covad Agreements.

     2. PAYMENT OF POST-PETITION AMOUNT

     Ardent covenants and agrees that it will pay to Covad cash at closing in
the amount of $178,403.12, plus the Post-Petition Amount. Ardent and Covad
stipulate that if the Closing occurs on November 19, 2001, the Post-Petition
Amount will be $980,962.57. If the Closing occurs after November 19, 2001,
Ardent and Covad shall seek to agree on the final amount of the Post-Petition
Amount, and if they are unable to agree on such amount, the final amount shall
be determined by the Bankruptcy Court on motion after notice. At the Closing,
Ardent shall pay so much of the Post-Petition Amount as is not disputed between
Ardent and Covad or as determined by the Bankruptcy Court, as applicable. Such
amount however, will in all events exceed $1,000,000.00. Upon such payment of
the entire Post-Petition Amount and pursuant to section 365(k) of the Bankruptcy
Code, Ardent shall be relieved from any further liability with respect to the
Covad Agreements arising after Closing. In addition, Ardent shall remain liable,
and shall pay when due, additional costs and charges that will accrue as of the
Closing Date but which are not invoiced at that time (e.g. disconnect charges,
cancellation fees, etc.)

     3. ASSUMPTION, ASSIGNMENT AND RESTATEMENT OF COVAD AGREEMENTS

          (a) Covad hereby consents to the assumption and assignment by Ardent
to NAS of all liabilities and obligations of Ardent under the Covad Agreements.

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          (b) NAS and Covad hereby agree that the Services Agreement shall be
restated so as to conform in all material respects to the DSL Services
Agreement, a form of which is attached hereto as EXHIBIT 3.

          (c) NAS and Covad hereby agree that the Covad ISP Agreement shall be
restated so as to conform in all material respects to the DSL+IP Services
Agreement, a form of which is attached hereto as EXHIBIT 4.

          (d) NAS and Covad hereby agree that any costs or fees associated with
              the services rendered by Covad to NAS under the Covad Agreements
              shall be based on "Tier 3" for end-user lines among the Acquired
              Assets and "Tier 4" for all other lines, as described more fully
              in the DSL and DSL + IP Services Agreement.

          (e) NAS hereby grants Covad a security interest in all of the Covad
              supplied lines among the Acquired Assets to secure payment of the
              monthly charges relating to the Covad supplied lines among
              Acquired Assets.

     4. OPERATIONAL PLATFORM FOR ACQUIRED ASSETS

          (a) NAS agrees that all Covad supplied end-user lines among the
              Acquired Assets shall remain on the Covad network and will not be
              moved to the separate NAS network not provided by Covad. In the
              event that an end-user circuit is cancelled and re-provisioned or
              otherwise serviced on the NAS network or a non-Covad network, NAS
              shall pay Covad $750.00 (seven hundred and fifty dollars)
              ("Transfer Charge") per end-user circuit (one thousand five
              hundred dollars) in addition to all cancellation and disconnect
              fees. The Transfer Charge shall not apply to lines cancelled or
              disconnected in the normal course of business and that are not
              repositioned or otherwise serviced on a non-Covad network.

          (b) NAS agrees that a minimum of 75% of Covad supplied end-user lines
              among the Acquired Assets shall be migrated to Covad's DSL + IP
              platform within 90 days of closing. NAS shall submit a plan to
              affect this migration within 30 days of closing. To the extent
              that NAS wishes to migrate less than 75%, it shall submit a plan
              to Covad identifying the end-user lines that it will not migrate
              to DSL + IP within 30 days of Closing. Covad, in its sole
              discretion shall have the right to reject the proposal to maintain
              lines on the DSL only platform. In any event, the percentage of
              lines migrated to DSL + IP within 90 days shall not fall below 60%
              of the Acquired Assets. In the event that NAS fails to migrate 75%
              of Covad supplied lines among the Acquired Assets within 90 days,
              Covad, in its sole discretion, shall have the right to charge for
              DSL + IP pricing for lines that have not been operationally
              transitioned until the percentage of lines being charged for
              DSL + IP equals 75%. Pricing for the lines not migrated shall
              reflect the representative mix of lines as of Closing. If the
              migration to Covad's DSL+IP platform is not accomplished within
              the specified timeframe due to failure to perform by Covad, all
              lines that have not been migrated shall be priced for DSL only
              according to the terms agreed to herein.

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          (c) NAS shall not be liable for any of the normal non-recurring
              charges associated with transfer of lines from Ardent to NAS or
              from DSL only to DSL + IP.

          (d) NAS and Covad agree that if Covad or its successor(s) fails to
              perform under the terms of the Services Agreements as attached in
              Exhibit 4, NAS shall not be liable for the Transfer Charge in the
              event that it migrates or transitions end user lines from the
              Acquired Assets.

     5. CLOSING

     The Parties' obligations hereunder are subject to the condition that Covad
shall have received a wire transfer of the $3,000,000.00 according to the
following wire instructions:

              Covad Communications Company
              Acct # 4038-832663
              ABA# 121 000 248
              Wells Fargo Bank
              420 Montgomery Street
              San Francisco, CA 94104

     6. GENERAL PROVISIONS

          (a) No amendment, waiver or consent with respect to any provision of
this Agreement shall in any event be effective, unless the same shall be in
writing and signed by the Parties, and then such amendment, waiver or consent
shall be effective only in the specific instance and for the specific purpose
for which given.

          (b) Any notice required to be given hereunder shall be sufficient if
in writing, and sent by courier service (with proof of service), facsimile
transmission, hand delivery (with proof of service) or certified or registered
mail (return receipt requested and first-class postage pre-paid), addressed as
follows:

          If to NAS:
              Network Access Solutions Corporation
              Three Dulles Tech Center
              13650 Dulles Technology Drive
              Herndon, Virginia 20171
              Attention: Mark Scott
              Facsimile: 703-793-5010

          With a copy to:
              Shaw Pittman
              2300 N Street, N.W.
              Washington, DC 20037
              Attention: Thomas J. Catliota, Esq.
              Facsimile: 202-663-8007

          If to Covad:
              Covad Communications Company
              4250 Burton Drive
              Santa Clara, CA 95054

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              Attention: Claude T. Tolbert, III
              Facsimile: 408-987-1603

          With a copy to:
              Covad Communications Company
              4250 Burton Drive
              Santa Clara, CA 95054
              Attention: General Counsel
              Facsimile: 408-987-1111

          If to Ardent, Inc. or Ardent Communications, Inc.:
              1820 North Fort Myer Drive
              Arlington, VA 22209
              Attention: Amit Rikhy
              Facsimile: 703-247-6770

          With a copy to:
              Swidler Berlin Shereff Friedman
              3000 K Street, N.W.
              Suite 300
              Washington, DC 20007
              Attention: Michael J. Lichtenstein, Esq.
              Facsimile: 202-424-7643

(or to such address as any party shall specify by written notice so given), and
shall be deemed to have been delivered as of the date so personally delivered or
mailed.

          (c) Each provision of this Agreement shall be construed in such a
manner so as to give such provision the fullest legal force and effect possible.
To the extent any provision hereof (or part of such provision) is held to be
unenforceable or invalid when applied to a particular set of facts, or
otherwise, the unenforceability or invalidity of such provisions (or part
thereof) shall not affect the enforceability or validity of the remaining
provisions hereof (or the remaining parts of such provision), which shall remain
in full force and effect, nor shall such unenforceability or invalidity render
such provision (or part thereof) inapplicable to other facts in the context of
which such provision (or part thereof) would be held legally enforceable and/or
valid.

          (d) This Agreement shall inure to the benefit of, and shall be binding
upon, the Parties and their respective heirs, executors or administrators,
personal or legal representatives, successors and assigns.

          (e) The headings in this Agreement are inserted for convenience and
reference only and are not intended to be used in construing or interpreting any
of the provisions of this Agreement.

          (f) This Agreement shall be construed and enforced in accordance with
the internal laws of the State of Delaware, without resort to any conflicts or
choice of laws principles.

          (g) This Agreement may be executed in two (2) or more counterparts,
each of which shall be deemed an original, but all of which together shall
constitute the same instrument.

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                             [SIGNATURES NEXT PAGE]

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     IN WITNESS WHEREOF, each of the Parties has executed this Agreement as of
the day and year first above written.

                                 NETWORK ACCESS SOLUTIONS CORPORATION

                                 By: /s/ JON AUST
                                     ------------
                                 Name: Jon Aust
                                 Title: CEO

                                 COVAD COMMUNICATIONS COMPANY

                                 By: /s/ Claude T. Tolbert III
                                     -------------------------
                                 Name: Claude T. Tolbert III
                                 Title: Vice President, Corporate Development

                                 ARDENT, INC.

                                 By: /s/ AMIT D. RIKHY
                                     -----------------
                                 Name: Amit D. Rikhy
                                 Title: CFO

                                 ARDENT, INC.

                                 By: /s/ AMIT D. RIKHY
                                     -----------------
                                 Name: Amit D. Rikhy
                                 Title: CFO

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                                                                       EXHIBIT 1

                             FORM OF PROMISSORY NOTE

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                                                                       EXHIBIT 2

                            FORM OF LETTER OF CREDIT<Page>

                            SECOND AMENDMENT OF LEASE

                                                                   Exhibit 10.56

     This Second Amendment of Lease dated February 14, 2002, between Dulles
Tech, Inc., ("Landlord") and Network Access Solutions Corporation, ("Tenant").

                                   WITNESSETH:

     WHEREAS, Landlord and Tenant entered into a lease dated October 27, 1999 as
amended March 1, 2000, (the "Lease") for certain premises consisting of 113,093
rentable square feet being the entire square footage of the building located at
13650 Dulles Technology Drive, Herndon, Virginia (the "Building"), (the
"Premises") all as more particularly described in the Lease, and

     WHEREAS, Tenant assigned the fourth and fifth floors of the Premises to SBC
Asset Management, Inc. by Assignment and Assumption of Leasehold Interest and
Landlord's Consent to Assignment dated May 1, 2002, and

     WHEREAS, Landlord brought suit against Tenant for non-payment of rent, and
in settlement of such suit Tenant is desirous of reducing the size of its
remaining Premises and Landlord is agreeable to same,

     NOW THEREFORE, in consideration of the mutual benefits passing between the
parties and for other good and valuable consideration, the receipt and
sufficiency of which are hereby mutually acknowledged, the parties hereto agree
as follows:

1.  Notwithstanding anything contained in Section 2.2 of the Lease to the
    contrary the Term of the Lease shall be deemed to mean a period of seven (7)
    years commencing March 1, 2002 (the Commencement Date") and expiring
    February 28, 2009, (the "Expiration Date"), (the "New Term").

2.  Notwithstanding anything contained in Section 2.1 of the Lease to the
    contrary, effective as of the Commencement Date the term "Premises" as set
    forth in the Lease shall be deemed to mean the following: a) 9,362 rentable
    square feet being a portion of the first floor of the Building, and b)
    22,397 rentable square feet being the entire second floor of the Building,
    for a total of 31,759 rentable square feet, (for purposes of this Second
    Amendment of Lease, the "New Premises"), as shown on the attached
    Exhibit "A".

3.  Tenant currently occupies the New Premises and accepts them in their "as is"
    condition. Tenant acknowledges and agrees that it is surrendering to
    Landlord and Landlord is accepting from Tenant 10,397 rentable square feet
    on the first floor of the Building and 23,656 rentable square feet on the
    third floor of the Building (the "Surrendered Premises"). Tenant shall
    deliver the Surrendered Premises to Landlord, free of occupancy by 5:00pm on
    February 28, 2002. Tenant will remove its personal property by March 8,
    2002. Tenant will pay a storage rent for the period of March 1-March 8,
    2002, of $6,926.96, based on $13.36 per rentable square foot. Tenant shall
    not remove any property or cabling that is the property of Landlord or was
    paid for by the Tenant Improvement Allowance provided to Tenant by Landlord
    in the construction of the Surrendered Premises. Notwithstanding the
    foregoing Tenant shall provide reasonable

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    access to Landlord and its agents, commencing February 15, 2002 for purposes
    of Landlord's marketing of the Surrendered Premises.

4.  The Base Rent for the New Premises during the New Term shall be as follows:

<Table>
<Caption>
                                             PER RENTABLE
YEAR                                          SQUARE FOOT             ANNUALLY          MONTHLY
----                                          -----------             --------          -------
<S>                                              <C>                 <C>               <C>
Year 1 March 1, 2002-February 28, 2003           $24.50              $778,095.50       $64,841.29

Year 2 March 1, 2003-February 29, 2004           $25.00              $793,975.00       $66,164.58

Year 3 March 1, 2004-February 28, 2005           $25.50              $809,854.50       $67,487.88

Year 4 March 1, 2005-February 28, 2006           $27.00              $857,493.00       $71,457.75

Year 5 March 1, 2006-February 28, 2007           Base Rent for Year 4 increased by 2.5%

Year 6 March 1, 2007-February 29, 2008           Base Rent for Year 5 increased by 2.5%

Year 7 March 1, 2008-February 28, 2009           Base Rent for Year 6 increased by 2.5%
</Table>

5.  The term "Base Year" for the New Term shall mean calendar year 2002.

6.  Section 3.1 (c) of the Lease is hereby deleted.

7.  Section 3.2 (b) of the Lease is amended by deleting in line 6 the term "one
    hundred percent (100%)" and substituting therefor: "ninety five percent
    (95%)"

8.  Section 3.3 of the Lease is amended as follows:
       i)  wherever in section (a) the words and number: "One Million Six
           Hundred Thousand and no/100s Dollars ($1,600,000.00)" appears it is
           deemed deleted and the following substituted therefor: "Three Hundred
           Twenty Four Thousand Two Hundred Six and no/100s Dollars
           ($324,206.00)".

       ii) section (b) is deleted in its entirety.

9.  Section 4.1 (a) (ii) is amended by adding at the end thereof the following:
       "Tenant shall be required to pay for HVAC services provided beyond the
       standard hours set forth herein monthly in advance, by the first of each
       month. Tenant recognizes that failure by Tenant to make such advance
       payment shall permit Landlord to cease such additional services and
       Landlord shall have no liability to Tenant arising from such cessation of
       additional services."

10. Section 4.3 of the Lease is amended by deleting the fourth and fifth
    sentences of such section.

11. Section 6.1 (b) is deleted in its entirety.

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12. Section 7.3 (a), second paragraph, is amended in line 4 by deleting:
    "$250,000)" and substituting therefor: "$75,000)"

13. Notwithstanding anything contained in Section 8.2 to the contrary, during
    the first six (6) months following the Commencement Date Tenant shall not be
    entitled to any notice in the event of a monetary default and the failure to
    pay any monies due Landlord, under the terms of the Lease, within five (5)
    days after its due date shall constitute a default, without the necessity of
    notice or an opportunity to cure.

14. Section 10.1 is amended as follows: "Notwithstanding anything contained in
    Section 10.1 to the contrary Landlord shall not be obligated to obtain an
    SNDA from any future mortgagee or holder of a deed of trust."

15. Section 11.12 of the Lease is deleted in its entirety.

16. Section 11.13 of the Lease is amended by deleting wherever it appears in
    this section the number "five hundred thirty one (531)" and substituting
    therefor: one hundred forty nine(149)". The second sentence of the section
    is hereby deleted.

17. Exhibit C is deleted in its entirety

18. Exhibit E shall have no application to the New Premises.

19. In the event that the space configuration on the first floor does not
    provide unrestricted access to the common areas, stairwells and elevators
    for the first floor Surrendered Space, Tenant, at its sole cost and expense,
    shall make such modifications to the first floor as Landlord may direct to
    provide such unrestricted access. Tenant currently has a security system in
    place for access to the Surrendered Space. Tenant shall cooperate with
    Landlord to effect a prompt transfer of such access to Landlord and provide
    Landlord in the interim with access to the Surrendered Space.

20. Landlord and Tenant acknowledge that the Lease as originally drafted was
    drafted with the intent that Tenant was a single tenant occupying the entire
    Building. Tenant no longer occupies the entire Building. As such any
    language in the Lease that was applicable to a tenant occupying the entire
    Building shall be deemed modified so that if applicable, in Landlord's
    reasonable judgment, the provision shall apply to a tenant occupying a
    proportionate part of the Building.

21. Landlord and Tenant acknowledge and agree that this Second Amendment of
    Lease is contingent upon the execution and compliance by Tenant of certain
    obligations set forth in a Settlement Agreement between Landlord and Tenant
    dated February 15, 2002 and that the failure of Tenant to comply with the
    obligations set forth in that Settlement Agreement render this Second
    Amendment of Lease null and void and of no force or effect. Tenant
    acknowledges and agrees that in entering into this Second Amendment of
    Lease, the Tenant is receiving substantial benefits and that those benefits
    constitute "new consideration" within the meaning of the federal Bankruptcy
    Code. Tenant further acknowledges that payments made to Landlord pursuant to
    the Settlement Agreement do not constitute "preferences" as such word is
    defined under the Bankruptcy Code of the United States if Tenant should file
    for Bankruptcy Court protection within ninety (90) days of the making of
    such payments to Landlord. Tenant further agrees that in the event

<Page>

    that Tenant files for Bankruptcy Court protection within such ninety(90) day
    period and the payments made pursuant to the Settlement Agreement are deemed
    "preferences" that Landlord shall be entitled to claim against the bankrupt
    estate of Tenant all damages and amounts as Landlord had prior to the
    execution of the Settlement Agreement and this Second Amendment of Lease.
    Neither Tenant, not any affiliate or subsidiary of Tenant, nor any of its
    affiliates or subsidiaries, may make any claim whatsoever that payments made
    pursuant to the Settlement Agreement to Landlord constitute a preferential
    payment or fraudulent conveyance in, or in relation to, any bankruptcy
    filing by Tenant.

22. Landlord and Tenant each represent and warrant to the other that neither of
    them has employed or dealt with any broker, agent or finder in carrying on
    the negotiations relating to this Second Amendment of Lease. Tenant shall
    indemnify and hold Landlord harmless from and against any claim or claims
    for brokerage or other commissions asserted by any other broker, agent or
    finder engaged by Tenant or with whom Tenant has dealt. It is specifically
    acknowledged and agreed that Schneider & Associates is Tenant's agent and
    that Landlord has no obligation to pay any fee to Schneider & Associates.

23. Other than as amended herein all other terms, provisions and conditions of
    the Lease are hereby ratified and confirmed.

     IN WITNESS WHEREOF the parties hereto set their hand the day and year first
written above:

ATTEST:                                     LANDLORD:

                                            DULLES TECH, INC.

By: /s/ CARMEN TAVERAS CRUZ                 By: /s/ CHARLES SCHOUTEN
    -----------------------                     --------------------
        Carmen Taveras Cruz                         Charles Schouten
            Secretary                                   President

ATTEST:                                     TENANT:

                                            NETWORK ACCESS SOLUTIONS CORPORATION

By: /s/ W.R. SMEDBERG                       By: /s/ JON AUST
   ------------------                           ------------
     William R. Smedberg                            Jon Aust
         Secretary                                    CEO

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