RFC 882 (rfc882) - Page 2 of 31
Domain names: Concepts and facilities
Alternative Format: Original Text Document
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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