SECOND AMENDMENT TO 1996 REVOLVING CREDIT AGREEMENT


     THIS SECOND  AMENDMENT  TO 1996  REVOLVING  CREDIT  AGREEMENT  (the "Second
Amendment"),  dated as of December 27,  1996,  is intended to amend the terms of
the 1996 Revolving Credit Agreement (the "Agreement") dated as of June 28, 1996,
among DATA TRANSMISSION NETWORK CORPORATION, FIRST NATIONAL BANK OF OMAHA, FIRST
NATIONAL  BANK,  WAHOO,  NEBRASKA,  NBD  BANK,  NORWEST  BANK  NEBRASKA,   N.A.,
AGAMERICA,  FCB  (assignee of FARM CREDIT  SERVICES OF THE MIDLANDS,  PCA),  THE
SUMITOMO BANK, LIMITED, MERCANTILE BANK OF ST. LOUIS, N.A., FIRST BANK, NATIONAL
ASSOCIATION,  and THE BOATMEN'S  NATIONAL  BANK OF ST. LOUIS,  as amended by the
First Amendment to 1996 Revolving Credit Agreement (the "First Amendment") dated
as of July 31,  1996.  The parties to this Second  Amendment  shall  include the
original parties to the Agreement, BANK OF MONTREAL, a Canadian bank represented
by its office at 430 Park Avenue,  New York, New York, 10022  ("Montreal"),  and
LASALLE NATIONAL BANK, a national banking  association  being represented by its
office at One  Metropolitan  Square,  211 North  Broadway,  St. Louis,  Missouri
63102.  All terms and conditions of the Agreement shall remain in full force and
effect except as expressly  amended herein.  All capitalized  terms herein shall
have their respective  meanings set forth in the Agreement.  The Agreement shall
be amended as set forth below.

         Section 1.        The following definitions of "Article I: Definitions"
                           of the Agreement shall be amended to read as follows:

         Farm Credit:               AgAmerica,  FCB, a  farm  credit bank doingb
                                    business  at 206 South 19th  Street,  Omaha,
                                    Nebraska  68102-1745,  as  assignee  of Farm
                                    Credit Services of the Midlands, P.C.A.

         Notes:                     (i) The Revolving Credit Notes, the Convert-
                                    ed  Notes  and  Existing  Term  Notes,   the
                                    Acquisition   Notes,   and  such  additional
                                    similar  notes as may be issued  to  certain
                                    additional  Lenders,   and  all  extensions,
                                    renewals,  and  substitutions  of or for the
                                    foregoing;  and (ii) notes and,  in the case
                                    of interest rate protection contracts,  such
                                    contracts  evidencing the obligations of the
                                    Borrower  to any  Lender  under the  Related
                                    Bank Debt.

         Related Bank Debt:         The aggregate unpaid balance of all indebt-
                                    edness, now or hereafter existing (including
                                    future  advances) under (i) the Related Loan
                                    Agreement,  including,  without  limitation,
                                    the amounts  outstanding under those certain
                                    promissory notes from the Borrower to FNB-O,
                                    FirsTier  and FNB-W  dated as of October 13,
                                    1992,   and   December  7,  1992,   and  all
                                    extensions,  renewals,  and substitutions of
                                    or  for  the  foregoing;  and  (ii)  certain
                                    interest rate protection  contracts  entered
                                    into from time to time by the Borrower  with
                                    one or more of the Lenders.

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         Total Indebtedness:        All loans and other obligations   of  the
                                    Borrower  and  its   Subsidiaries,   without
                                    duplication,  for borrowed money (including,
                                    without limitation,  the indebtedness due to
                                    the  Lenders)  regardless  of  the  maturity
                                    thereof  but such  term  shall  not  include
                                    subordinated  debt of the Borrower,  as such
                                    term is  defined  in the  definition  of Net
                                    Worth up to $15,000,000 if such subordinated
                                    debt  is  existing  on  May  3,  1996.   For
                                    purposes  of  this   definition   of  "Total
                                    Indebtedness,    "indebtedness    under   an
                                    interest  rate  protection  agreement  shall
                                    mean  the  amount  if  any,  at the  time of
                                    determination,  of the unpaid  Interest Rate
                                    Protection   Contract   Amounts;   provided,
                                    however,  that solely for purposes of voting
                                    under this Agreement by the Lenders,  "Total
                                    Indebtedness" will not include such Interest
                                    Rate Protection Contract Amounts.

         Section 2.        The following definitions shall be added to Article I
                           of the Agreement:

         Interest Rate
         Protection Contract
         Amounts:                   "Interest Rate Protection Contract Amounts"
                                    shall  mean  amounts  due from the  Borrower
                                    under  interest  rate  protection  contracts
                                    between the Borrower and one or more Lenders
                                    as to (i) the interest  differential amounts
                                    due in respect of periodic  netting payments
                                    under any such contract, and (ii) any amount
                                    due as a result of  marking  to  market  the
                                    Borrower's   obligations   under   any  such
                                    contract upon the  occurrence of an event of
                                    default  under,  or other early  termination
                                    of, such  contract;  in either case  without
                                    inclusion of fees and other expenses related
                                    to  such   contract.   Such   Interest  Rate
                                    Protection   Contract   Amounts   shall   be
                                    reported   in   writing  to  FNB-O  and  the
                                    Borrower  by the  applicable  Lender at such
                                    times as shall be  appropriate  to carry out
                                    the intent of this Agreement.

         LaSalle:                   LaSalle  National  Bank, a national  banking
                                    association  having its  principal  place of
                                    business  at  135  South   LaSalle   Street,
                                    Chicago, Illinois 60603.

         Section 3.        On the date of this Second  Amendment,  the  Borrower
                           shall  prepay in full the  principal  amount  of, and
                           accrued  interest through such date on, the Revolving
                           Credit  Note in the  principal  amount of  $9,603,600
                           payable to Farm Credit,  which Revolving  Credit Note
                           has been assigned to AgAmerica.  Simultaneously, upon
                           (a)  receipt  by  the  Borrower  of  the   $9,603,600
                           Revolving Credit Note payable to Farm Credit,  marked
                           "canceled and paid in full" by AgAmerica, and (b) the

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                           payment of $7,469,462 in immediately available  funds
                           from   LaSalle  to  FNB-O  for  the  account  of  the
                           Borrower,  the  Borrower  shall  issue to  LaSalle  a
                           Revolving  Credit  Note in the  principal  amount  of
                           $9,603,600,   such   Revolving   Credit  Note  to  be
                           substantially  in the form  attached  to this  Second
                           Amendment as  Attachment A.  Thereafter,  (i) LaSalle
                           shall be deemed  to be a  "Lender"  and a  "Revolving
                           Lender" under the Agreement and AgAmerica shall cease
                           to be a "Lender" and a "Revolving Lender" thereunder;
                           and (ii) the  reference  to Farm Credit in clause (v)
                           of Section 2.1 of the Agreement shall be deemed to be
                           a reference to LaSalle.
         Section 4.        Section 2.6 of the Agreement shall be amended to read
                           as follows:

                           2.6  Payments.   All   obligations   of  the Borrower
                           under the Related  Bank Debt (other than  obligations
                           under  any  interest   rate   protection   contract),
                           Revolving  Credit Notes and Converted Notes and under
                           the other  Operative  Documents  shall be  payable in
                           immediately  available  funds in lawful  money of the
                           United States of America at the  principal  office of
                           FNB-O in Omaha,  Nebraska or at such other address as
                           may be designated  by FNB-O in writing.  In the event
                           that a payment day is not a Business Day, the payment
                           shall be due on the next succeeding Business Day.

         Section 5.        (a)      The  first  sentence  of Section 7.1 of the
                                    Agreement   shall  be  amended  to  read  as
                                    follows:

                           FNB-O  will  act  as  sole   servicer  of  the  loans
                           evidenced by the Notes (other than in connection with
                           interest rate protection contracts).

                           (b)      The  penultimate  sentence  of  Section  7.1
                                    shall be amended to read as follows:

                           Notwithstanding the foregoing,  unanimous approval of
                           the  applicable  Lenders under the  respective  Notes
                           shall  be  required   for:   (i)  any   reduction  or
                           compromise  of the  principal  loan  amount  of  such
                           Notes,  the  amount or rate of  interest  accrued  or
                           accruing thereon or the fees due hereunder;  and (ii)
                           extension of the date of any scheduled  payment;  and
                           unanimous   consent  of  all  the  Lenders  shall  be
                           required  for  (iii)   permitting   the  sale  of  or
                           releasing  the  security  interest  of the Lenders in
                           Collateral  which  comprises  more  than ten  percent
                           (10%)  of net  book  value  of  fixed  assets  of the
                           Borrower;  and (iv) any  amendment of Sections 7.1 or
                           7.2 hereof.

         Section 6.        Subsection 7.2(bb) of the Agreement shall be amended
                           to read as follows:

                                    (bb)  second,  pari passu among the Lenders,
                           based on their  respective  pro  rata  shares  of the
                           funds to be  applied.  Each  Lender's  pro rata share
                           shall be equal to a fraction,  (x) the  numerator  of
                           which shall be the total

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                           principal loan amount then outstanding which is owing
                           to each  such  Lender  under its  Notes,  and (y) the
                           denominator  of which  shall be the  total  principal
                           loan  amount then  outstanding  which is owing to the
                           Lenders  under  all  Notes.  As  to  any  Note  which
                           represents  an  obligation  of the Borrower to one or
                           more  Lenders  under  an  interest  rate   protection
                           contract,  "principal  loan amount then  outstanding"
                           shall mean, as of the date of  determination by FNB-O
                           of the  Lenders'  respective  pro  rata  shares,  the
                           amount,   if  any,  of  the  unpaid   Interest   Rate
                           Protection Contract Amounts.

         Section 7.        The following  sentence shall be added to  the end of
                           Section 7.4 of the Agreement:

                           For purposes of this Section 7.4,  "Notes"  shall not
                           include interest rate protection contracts.

         Section 8.        The Borrower  hereby restates for the benefit of the
                           Lenders the representations and warranties  contained
                           in Article III of the Agreement and affirms that such
                           representations  and  warranties are true and correct
                           as  of   the   date   of   this   Second   Amendment.
                           Notwithstanding the foregoing, representations of the
                           Borrower   as  to  UCC  filings  in  respect  of  the
                           Collateral   are  hereby   amended  to  reflect  such
                           additional  filings  as shall have been made in favor
                           of the Lenders.

         Section 9.        The  Lenders  hereby  acknowledge  and  consent  to
                           the Third Amendment to the 1996 Term Credit Agreement
                           dated as of the date hereof among the parties  herein
                           (not including Boatmen's).

         Section  10.      This Second  Amendment may  be  executed  in  several
                           counterparts  and such  counterparts  together  shall
                           constitute one and the same instrument.

         Section 11.       This  Second  Amendment  shall be effective upon the
                           execution and delivery thereof by the parties hereto.
                           References in the Notes to the Loan  Agreement  shall
                           be deemed  amended to refer to the Loan  Agreement as
                           amended  by  the  First  Amendment  and  this  Second
                           Amendment.

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         IN WITNESS WHEREOF, the undersigned have executed this SECOND AMENDMENT
TO 1996 REVOLVING CREDIT AGREEMENT dated as of December 27, 1996.


                                            DATA TRANSMISSION NETWORK
                                            CORPORATION


                                            By     /s/  Brian Larson
                                                  ------------------------
                                            Title: Vice President, CFO,
                                                   Secretary and Treasurer



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                                            FIRST NATIONAL BANK OF OMAHA


                                            By          /s/  JP Bonham
                                                       ------------------------
                                            Title:      Vice President






NOTICE: A credit  agreement must be in writing to be enforceable  under Nebraska
law. To protect you and us from any  misunderstandings  or disappointments,  any
contract,  promise,  undertaking,  or offer to forebear repayment of money or to
make any other financial  accommodation in connection with this loan of money or
grant or extension of credit,  or any amendment of,  cancellation of, waiver of,
or  substitution  for any or all of the terms or provisions of any instrument or
document executed in connection with this loan of money or grant or extension of
credit, must be in writing to be effective.

                                            INITIALED:   /s/  BL
                                                       ------------------------

                                            Borrower





                                        6


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                                            THE SUMITOMO BANK, LIMITED


                                            By       /s/ Teresa A. Lekich
                                                  ------------------------
                                            Title:  Vice President


                                            By         /s/  H.W. Redding
                                                  ------------------------
                                            Title:  Vice President & Manager







NOTICE: A credit  agreement must be in writing to be enforceable  under Nebraska
law. To protect you and us from any  misunderstandings  or disappointments,  any
contract,  promise,  undertaking,  or offer to forebear repayment of money or to
make any other financial  accommodation in connection with this loan of money or
grant or extension of credit,  or any amendment of,  cancellation of, waiver of,
or  substitution  for any or all of the terms or provisions of any instrument or
document executed in connection with this loan of money or grant or extension of
credit, must be in writing to be effective.

                                            INITIALED:   /s/  BL
                                                       ------------------------


                                            Borrower



                                        7


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                                            FIRST NATIONAL BANK,
                                            WAHOO, NEBRASKA


                                            By        Elizabet Rezac
                                                  ------------------------
                                            Title:    2nd Vice President








NOTICE: A credit  agreement must be in writing to be enforceable  under Nebraska
law. To protect you and us from any  misunderstandings  or disappointments,  any
contract,  promise,  undertaking,  or offer to forebear repayment of money or to
make any other financial  accommodation in connection with this loan of money or
grant or extension of credit,  or any amendment of,  cancellation of, waiver of,
or  substitution  for any or all of the terms or provisions of any instrument or
document executed in connection with this loan of money or grant or extension of
credit, must be in writing to be effective.

                                            INITIALED:   /s/  BL
                                                       ------------------------

                                            Borrower



                                        8


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                                            NBD BANK


                                            By         /s/   D.J. Pienta
                                                       ------------------------
                                            Title:     Vice President










NOTICE: A credit  agreement must be in writing to be enforceable  under Nebraska
law. To protect you and us from any  misunderstandings  or disappointments,  any
contract,  promise,  undertaking,  or offer to forebear repayment of money or to
make any other financial  accommodation in connection with this loan of money or
grant or extension of credit,  or any amendment of,  cancellation of, waiver of,
or  substitution  for any or all of the terms or provisions of any instrument or
document executed in connection with this loan of money or grant or extension of
credit, must be in writing to be effective.

                                            INITIALED:


                                            Borrower



                                        9


                                     - 97 -
<PAGE>






                                            NORWEST BANK NEBRASKA, N.A.



                                            By
                                            Title:












NOTICE: A credit  agreement must be in writing to be enforceable  under Nebraska
law. To protect you and us from any  misunderstandings  or disappointments,  any
contract,  promise,  undertaking,  or offer to forebear repayment of money or to
make any other financial  accommodation in connection with this loan of money or
grant or extension of credit,  or any amendment of,  cancellation of, waiver of,
or  substitution  for any or all of the terms or provisions of any instrument or
document executed in connection with this loan of money or grant or extension of
credit, must be in writing to be effective.

                                            INITIALED:


                                            Borrower



                                       10


                                     - 98 -
<PAGE>






                                            AGAMERICA, FCB
                                            (assignee of FARM CREDIT
                                            SERVICES OF THE MIDLANDS, PCA)



                                            By
                                            Title:










NOTICE: A credit  agreement must be in writing to be enforceable  under Nebraska
law. To protect you and us from any  misunderstandings  or disappointments,  any
contract,  promise,  undertaking,  or offer to forebear repayment of money or to
make any other financial  accommodation in connection with this loan of money or
grant or extension of credit,  or any amendment of,  cancellation of, waiver of,
or  substitution  for any or all of the terms or provisions of any instrument or
document executed in connection with this loan of money or grant or extension of
credit, must be in writing to be effective.

                                            INITIALED:


                                            Borrower




                                       11


                                     - 99 -
<PAGE>






                                            MERCANTILE BANK OF ST. LOUIS, N.A.



                                            By
                                            Title:










NOTICE: A credit  agreement must be in writing to be enforceable  under Nebraska
law. To protect you and us from any  misunderstandings  or disappointments,  any
contract,  promise,  undertaking,  or offer to forebear repayment of money or to
make any other financial  accommodation in connection with this loan of money or
grant or extension of credit,  or any amendment of,  cancellation of, waiver of,
or  substitution  for any or all of the terms or provisions of any instrument or
document executed in connection with this loan of money or grant or extension of
credit, must be in writing to be effective.

                                            INITIALED:


                                            Borrower



                                       12


                                    - 100 -
<PAGE>




                                            FIRST BANK, NATIONAL ASSOCIATION



                                            By
                                            Title:










NOTICE: A credit  agreement must be in writing to be enforceable  under Nebraska
law. To protect you and us from any  misunderstandings  or disappointments,  any
contract,  promise,  undertaking,  or offer to forebear repayment of money or to
make any other financial  accommodation in connection with this loan of money or
grant or extension of credit,  or any amendment of,  cancellation of, waiver of,
or  substitution  for any or all of the terms or provisions of any instrument or
document executed in connection with this loan of money or grant or extension of
credit, must be in writing to be effective.

                                            INITIALED:


                                            Borrower



                                    13


                                    - 101 -
<PAGE>






                                            BOATMEN'S NATIONAL BANK OF ST. LOUIS



                                            By
                                            Title:










NOTICE: A credit  agreement must be in writing to be enforceable  under Nebraska
law. To protect you and us from any  misunderstandings  or disappointments,  any
contract,  promise,  undertaking,  or offer to forebear repayment of money or to
make any other financial  accommodation in connection with this loan of money or
grant or extension of credit,  or any amendment of,  cancellation of, waiver of,
or  substitution  for any or all of the terms or provisions of any instrument or
document executed in connection with this loan of money or grant or extension of
credit, must be in writing to be effective.

                                            INITIALED:


                                            Borrower



                                    14


                                    - 102 -
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                                            BANK OF MONTREAL


                                            By
                                            Title:






NOTICE: A credit  agreement must be in writing to be enforceable  under Nebraska
law. To protect you and us from any  misunderstandings  or disappointments,  any
contract,  promise,  undertaking,  or offer to forebear repayment of money or to
make any other financial  accommodation in connection with this loan of money or
grant or extension of credit,  or any amendment of,  cancellation of, waiver of,
or  substitution  for any or all of the terms or provisions of any instrument or
document executed in connection with this loan of money or grant or extension of
credit, must be in writing to be effective.

                                            INITIALED:


                                            Borrower






3796v2

                                    15



                                    - 103 -
<PAGE>






                                            LASALLE NATIONAL BANK


                                            By
                                            Title:






NOTICE: A credit  agreement must be in writing to be enforceable  under Nebraska
law. To protect you and us from any  misunderstandings  or disappointments,  any
contract,  promise,  undertaking,  or offer to forebear repayment of money or to
make any other financial  accommodation in connection with this loan of money or
grant or extension of credit,  or any amendment of,  cancellation of, waiver of,
or  substitution  for any or all of the terms or provisions of any instrument or
document executed in connection with this loan of money or grant or extension of
credit, must be in writing to be effective.

                                            INITIALED:


                                            Borrower






 3796

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