<PAGE>   1

                                 AMENDMENT NO. 1
                                RESALE AGREEMENT
               BETWEEN APPLIEDTHEORY CORPORATION AND NYSERNET.ORG

      This Amendment No. 1 to the Resale Agreement (this Amendment") is made as
of April 18, 2000 by and between AppliedTheory Corporation, a Delaware
corporation (formerly NYSERNet.Com) ("AppliedTheory") and NYSERNet.org, a New
York corporation ("NYSERNet").

                                   BACKGROUND

      This Amendment is made with reference to the following facts:

      A.   NYSERNet and AppliedTheory are parties to that certain Resale
           Agreement dated as of 10/1/96 (the "Agreement").

      B.   The parties desire to amend the Agreement pursuant to the terms
           agreed upon in the Memorandum of Understanding dated 2/14/2000 as set
           forth below.

                               TERMS OF AMENDMENT

      Accordingly, in consideration of the mutual promises set forth below, the
parties hereby agree as follows:

   1. Paragraph 2.1 of Section 2 APPOINTMENT is deleted effective upon
      AppliedTheory's billing of NYSERNet for the 10th full OC-3 site
      connection.

   2. Paragraph 3.1 of "Section 3 TERM" is replaced with the following:

         3.1 This Agreement shall be effective from October 1, 1996 and shall
         extend to September 30, 2005. Thereafter, this Agreement will
         automatically renew for successive one (1) year terms unless either
         party notifies the other party of its intent not to renew at least
         sixty (60) days before the end of the term then in effect.

   3. Paragraphs 5.3.1 and 5.3.2 of "Section 5 OBLIGATIONS OF COM" are added:

         5.3.1 AppliedTheory pricing to NYSERNet for full OC3 ports is $45,000
         per month.

         5.3.2 Pricing for fractional OC-3 ports are to be determined. NYSERNet
         will receive preferential pricing.

   4. Paragraph 8.3 and 8.4 are added to Section 8 MISCELLANEOUS:

         8.3 NYSERNet commits to purchase a minimum of ten OC3 connections for
         its member institutions by 6/30/2001 and will make commercially
         reasonable efforts to meet the following schedule: 6 by 9/1/2000, an
         additional 2 by 12/31/2000, and an additional 2 by 6/30/2001.

   5. Paragraph 9.3 and 9.4 are added to "Section 9 PERIODIC REVIEW":

         9.3 AppliedTheory agrees to review pricing for Access Products with
         NYSERNet on or about 9/30/2002 and 9/30/2004. These reviews will also
         encompass a
<PAGE>   2
         comprehensive review of the AppliedTheory NYSERNet relationship
         including items listed in paragraph 7, below, and issues of interest to
         NYSERNet regarding the NYSERNet 2000 Network.

         9.4 AppliedTheory and NYSERNet shall mutually develop and enhance on an
         ongoing basis, a program plan for Customer Care which will document all
         procedures and processes for managing troubles and escalations within
         both organizations (the "Program Plan".) The Program Plan will also
         detail all standard and special customer services and service level
         agreements provided by AppliedTheory to NYSERNet.

   6. Paragraph 12.5 of "Section 12 TERMINATION" is added to the Agreement:

         12.5 NYSERNet member institutions may terminate their Access service
         agreements at will. The customary three-month penalty fee is reduced to
         two months. Termination of a member institutions' service agreement
         shall not affect the termination date of this Agreement.

   7. The following additional provisions are added:

         AppliedTheory and NYSERNet agree to expend mutual best efforts to
         develop the NYSERNet-AppliedTheory relationship with focus on areas of
         development to be determined and subject to change, per NYSERNet's
         priority. NYSERNet and AppliedTheory will establish a mutually agreed
         upon process for amending the list of NYSERNet development priorities.
         AppliedTheory and NYSERNet agree that either party may propose adding
         and/or removing items from the list, but that NYSERNet has the final
         authority to determine a project "completed." The list of development
         projects will be formalized, from time to time as the parties deem
         necessary, as amendments to this Agreement.

         The parties agree that the first priority for development projects will
         be creation of a mechanism(s) that NYSERNet customers purchasing
         services through this Amendment can use to measure the AppliedTheory
         service and to verify network performance within the AppliedTheory
         network and through egress points. This project will also include the
         development of a mutually agreed to set of performance levels, and will
         be completed no later than December 31, 2000

         AppliedTheory will honor NYSERNet's Downstream Policy as it may change
         from time to time during the term of this Agreement.

         For as long as NYSERNet buys its Internet access services exclusively
         from AppliedTheory, AppliedTheory commits to provide dedicated staff to
         NYSERNet in the following areas: account executive focused on
         relationship development and new business; and customer support
         coordinator. Other AppliedTheory staff will be assigned at reasonable
         levels of effort to work on areas of mutual interest from time-to-time
         as the list in paragraph 7, above, develops and is amended. Should
         NYSERNet acquire Internet access services from a third party,
         AppliedTheory will have the right to unilaterally determine levels of
         effort for account management and customer care. Levels for these
         services will not however be less than those identified in the then
         current AppliedTheory Customer Service Agreements for other
         AppliedTheory customers.
<PAGE>   3
         Authorized Customers (as defined in the Agreement), which are also
         Certified(1) NYSERNet Members, purchasing OC-3 Access Services, either
         new contracts or extensions to existing contracts have the option of
         selecting either an AppliedTheory Service Agreement or a NYSERNet
         Service Agreement(2). All terms and conditions of this Agreement apply
         regardless of which Service agreement NYSERNet Members choose.
         Communications to NYSERNet members about these options will be a
         NYSERNet responsibility and will be supported in principle and process
         by AppliedTheory sales.

         AppliedTheory's standard Service Agreement for Access is incorporated
         into this Amendment as Exhibit A. All terms and conditions contained in
         Exhibit A apply to NYSERNet's customers with the exception of those
         terms that have been modified by this Amendment (Downstreaming, and
         Termination Penalties.).

   8. This Amendment is effective as of the last signature hereto (the
      "Amendment Effective Date")

   9. All other terms and conditions of the Agreement not specifically amended
      herein shall remain in full force and effect.

      IN WITNESS WHEREOF, the parties have executed this Amendment.

     APPLIEDTHEORY CORPORATION      NYSERNET.ORG

     By:  /s/ Angelo A. Gencarelli III     By:  /s/ Dr. Timothy Lance
          ----------------------------          ------------------------------
     Name:  Angelo A. Gencarelli III       Name: Dr. Timothy Lance
            --------------------------           -----------------------------
     Title:  Vice President                Title: President & Chairman
            --------------------------            ----------------------------
     Date:  5/3/00                         Date:  4/18/00
            --------------------------            ----------------------------



--------

(1) Certified, for the purposes of this Agreement, means that the customer
understands and agrees that they are members of NYSERNet in good standing.

(2) The process for signing NYSERNet services agreements is to be defined in the
Program Plan.