Network Working Group                        Internet Architecture Board
Request for Comments: 1401                           Lyman Chapin, Chair
                                                            January 1993


         Correspondence between the IAB and DISA on the use of
                      DNS throughout the Internet

Status of this Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard.  Distribution of this memo is
   unlimited.

Abstract

   This memo reproduces three letters exchanged between the Internet
   Activities Board (IAB) and the Defense Information Systems Agency
   (DISA) regarding the importance of using the Domain Name System (DNS)
   throughout the Internet, and phasing out the use of older host name
   to address tables, such as "hosts.txt".

1.  Letter from the IAB to DISA

                                                   30 March, 1992

   To: Members of the Federal Networking Council,
       Members of the Federal Networking Advisory Council,
       Colonel Ken Thomas, Chairman,
           DoD Protocol Standards Steering Group, DISA/Center for
           Standards

   CC: C. J. Pasquariello, Associate Director, Center for Standards,
       LCDR, David Chappell, Executive Secretary,
           PSSG, DISA/Center for Standards
       Eduardo Schonborn, Dep Director/DDN PMO


   As the IAB, together with others in the Internet Engineering and
   Research Task Forces, contemplates the challenges inherent in dealing
   with an exponentially expanding Internet, the critical need for
   widespread adoption of a uniform Domain Name service is very
   apparent.

   The attached memorandum is offered by the Internet Activities Board
   for your consideration regarding technical policy concerning domain
   naming in the US portion of the Internet.  The proposed technical
   policy is recommended world-wide and will be offered as an RFC for
   that purpose.  Adoption of such a policy would, we believe, much
   enhance the operational efficiency of the existing world-wide
   Internet backbone and major networks dependent upon it, including the
   DDN Milnet.

   Your consideration of this policy question is urged in the strongest
   possible terms.  We would much appreciate hearing the views of the
   Protocol Standards Steering Group by April 20, 1992.

   Regards,

   A. Lyman Chapin
   Chairman, Internet Activities Board

Attachment

              The Domain Name System is an Internet Necessity

                         Internet Activities Board

                               February 1992

   Over the last several years, the Internet has evolved in size so
   extensively that it has become infeasible to provide directory
   services through a database maintained at a single, central
   repository.  Both the size and the dynamics of the required data make
   such an approach impractical.  Recognizing this problem several years
   ago [1], the Internet community has adopted the Domain Name System
   [2-5] as the principal means of achieving host name to IP address
   mappings.  During this time, almost the entire Internet has converted
   from the use of the static name-to-address mapping tables thus far
   centrally maintained at the DDN Network Information Center, to the
   use of the more dynamic, up-to-date address mapping provided by DNS
   mechanism.

   There are still large fractions of the Internet community which rely
   on the use of a centrally-maintained file ("hosts.txt") to accomplish
   this mapping function.  The MILNET community appears to have
   substantial pockets of dependence on table-driven mappings, for
   example.  Although a plan for achieving a MILNET transition to use of
   the Domain Name System was worked out in 1987, the transition is
   incomplete and, as a result, naming services (i.e., host name lookups
   on the MILNET) are many times still provided via static tables rather
   than the distributed, and far more accurate, Domain Name System.
   Ironically, most of the commercial, off-the-shelf software for TCP/IP
   supports the user of the Domain Name System, so a policy of uniform
   support and application of DNS would go a long way toward improving
   the Defense Department data communication infrastructure, insofar as
   it is dependent on TCP/IP to interconnect hosts on LANs and WANs.

   The use of different means for name-to-address mappings by different
   parties in the network community leads to unsynchronized and
   inconsistent databases, which inevitably result in reachability
   failures by users attempting to connect to network resources.
   Moreover, the special facilities of the Domain Name System, such as
   the MX (Mail eXchange) record, make it possible to include systems
   not directly on the Internet into the universe of addressable
   parties.  MX records also allow a network administrator to prioritize
   a list of alternative e-mail relays in case the final destination is
   not reachable.  Systems which do not support MX records, but rather
   still depend on the "hosts.txt" information, pose a serious obstacle
   to network connectivity, as well as to the operation and management

   of the highly connected Internet.

   Non-DNS systems on the Internet will eventually be confronted with
   the need to decide whether they want to continue as a part of the
   larger Internet community, or remain a rather small, non-conforming
   subset.  Should they choose not to conform to the otherwise accepted
   Domain Name System, they will have to accept the ramifications of
   this decision.  In particular, they will have to accept that the rest
   of the community may, indeed has already started to, essentially
   ignore those static files which reflect the principal non-DNS naming
   service.  The larger community has evolved so extensively beyond
   these configurations, that these files are not only obsolete as a
   technology, but also incomplete and often inaccurate in the present
   implementation.  Upon connecting a new host to the Internet, the
   great majority of the Internet community no longer considers the
   registration of host name/address updates to the NIC database a
   necessity, and rather focuses on updating the Domain name System.
   Therefore, today's NIC database, and the "hosts.txt" file generated
   from it, largely reflects only the non-DNS community, a tiny subset
   of the hundreds of thousands of entities configured into the Internet
   name space via the DNS.

   If the non-DNS users maintain a requirement for the use of static
   mapping tables, at least some mechanism should exist to augment the
   NIC data sets with additional information represented by the Domain
   Name System.  These more comprehensive tables, accompanied by a
   method to guarantee synchronization with the DNS, would significantly
   improve the accuracy of the information which non-DNS users apply to
   map between names and addresses.  However, this solution will not
   address the need for support of the richer DNS functionality by the
   NIC's system.  At a minimum, the incorporation of MX information into
   the NIC database is imperative for compatibility between the
   "hosts.txt" file and the DNS.  Network subcommunities which choose to
   maintain a separate and incompatible mapping system will have a
   partitioning effect on the subcommunities themselves, but also a
   detrimental impact on overall Internet operations.  Both end-users
   and system and network administrators will inevitably find themselves
   devoting considerable attention to tracing inconsistency problems
   arising from the discrepancy in mapping methods.

   The Internet Activities Board, recognizing the need for universal
   interoperability and consistent naming mechanisms, and benefitting
   from several years of experience with the Domain Name System, is
   advocating a policy that all connected components of the Internet
   community should adopt the DNS, and urges parties having policy-
   setting authority to adopt the same position and undertake to set
   deadlines for conversion to uniform use of DNS.

References

   1. J.B. Postel and J.K. Reynolds, Domain Requirements, RFC 920,
      October 1984.

   2. P.V. Mockapetris, Domain Names - Concepts and Facilities,
      RFC 1034, November 1987.

   3. P.V. Mockapetris, Domain Names - Implementation and Specification,
      RFC 1035, November 1987.

   4. M.K. Stahl, Domain Administrators Guide, RFC 1032, November 1987.

   5. M. Lottor, Domain Administrators Operations Guide, RFC 1033,
      November 1987.

   6. W.D. Lazear, MILNET Name Domain Transition, RFC 1031,
      November 1987.

2.  Letter from DISA to the IAB

                                                   16 APR 1992

   Mr. Lyman Chapin
   Chairman, Internet Activities Board
   BBN Communications
   Division of Bolt Beranek and Newman, Inc.
   150 Cambridge Park Dr.
   Chambridge, MA  02140

   Dear Mr. Chapin:

   We have received you letter concerning the adoption and use of the
   Domain Name System (DNS) throughout the Internet.  Since the DoD
   makes significant use of the Internet, we are very concerned with
   issues such as the DNS that potentially affect both performance and
   interoperability.  We have agreed to staff this issue to consider all
   the technical and economical impacts on DoD systems.  We will inform
   you of the decisions reached as the result of our reviews as son as
   they are completed.

                                   Sincerely,

                                   Kenneth A. Thomas
                                   Colonel, USA
                                   Chairman, Protocol Standards
                                     Steering Group (PSSG)

   Copy to:
   Mr. Pasquariello, Associate Director, Center for Standards
   Mr. Schonborn, Deputy Director/DDN PMO

3.  Letter from the IAB to DISA

   19 May, 1992

   Colonel Kenneth Thomas
   Chairman, Protocol Standards Steering Group
   Defense Information Systems Agency
   Fort Monmouth, NJ 07703-5613

   Dear Colonel Thomas,

   Thank you for your response to my letter concerning the adoption and
   use of the Domain Name System throughout the Internet.  I appreciate
   your willingness to devote resources to consider this issue, and look
   forward to hearing the results of the study.

   As LCDR David Chappell has suggested, it would be useful for us to
   arrange a meeting to discuss issues of mutual concern to DISA and the
   IAB.  I do not yet know if it will be feasible for me to arrange to
   meet with you in Ft. Monmouth in the near future (my travel schedule
   being somewhat oversubscribed), but will get in touch with you soon
   to find a suitable date and location.

   Regards,

   A. Lyman Chapin
   Chairman, Internet Activities Board
   BBN Communications 20/5b
   150 Cambridge Park Drive
   Cambridge, MA 02140

Security Considerations

   Security issues are not discussed in this memo.

Author's Address

   A. Lyman Chapin
   BBN Communications Corporation
   150 Cambridge Park Drive
   Cambridge, MA  02140

   Phone: 617-873-3133
   Fax:   617-873-4086

   Email: Lyman@BBN.COM