RFC 882 (rfc882) - Page 2 of 31

Domain names: Concepts and facilities

RFC 882                                                    November 1983
                                  Domain Names - Concepts and Facilities


      mailbox names, they have also created an increasingly large and
      irregular set of methods for identifying the location of a
      mailbox.  Some of these methods involve the use of routes and
      forwarding hosts as part of the mail destination address, and
      consequently force the mail user to know multiple address formats,
      the capabilities of various forwarders, and ad hoc tricks for
      passing address specifications through intermediaries.

      These problems have common characteristics that suggest the nature
      of any solution:

         The basic need is for a consistent name space which will be
         used for referring to resources.  In order to avoid the
         problems caused by ad hoc encodings, names should not contain
         addresses, routes, or similar information as part of the name.

         The sheer size of the database and frequency of updates suggest
         that it must be maintained in a distributed manner, with local
         caching to improve performance.  Approaches that attempt to
         collect a consistent copy of the entire database will become
         more and more expensive and difficult, and hence should be
         avoided.  The same principle holds for the structure of the
         name space, and in particular mechanisms for creating and
         deleting names; these should also be distributed.

         The costs of implementing such a facility dictate that it be
         generally useful, and not restricted to a single application.
         We should be able to use names to retrieve host addresses,
         mailbox data, and other as yet undetermined information.

         Because we want the name space to be useful in dissimilar
         networks, it is unlikely that all users of domain names will be
         able to agree on the set of resources or resource information
         that names will be used to retrieve.  Hence names refer to a
         set of resources, and queries contain resource identifiers.
         The only standard types of information that we expect to see
         throughout the name space is structuring information for the
         name space itself, and resources that are described using
         domain names and no nonstandard data.

         We also want the name server transactions to be independent of
         the communications system that carries them. Some systems may
         wish to use datagrams for simple queries and responses, and
         only establish virtual circuits for transactions that need the
         reliability (e.g. database updates, long transactions); other
         systems will use virtual circuits exclusively.





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