RFC 3172 (rfc3172) - Page 2 of 8

Management Guidelines & Operational Requirements for the Address and Routing Parameter Area Domain ("arpa")

RFC 3172                    arpa Guidelines               September 2001


   The DNS is also capable of supporting a translation in the opposite
   direction, from protocol values to the names of service entities.
   One approach in using the DNS in this fashion has been to transform
   protocol values into a hierarchically structured identifier space,
   and then use these transformed protocol value names as a DNS lookup
   key into the appropriate DNS name hierarchy.  A common use of this
   mechanism has been the reverse of the name to address lookup,
   allowing for an IPv4 address to be used to look up a matching domain
   name.  For example, the IP address 128.9.160.55 can be associated
   with the domain name "www.iab.org." by creating the DNS entry
   55.160.9.128.in-addr.arpa." and mapping this entry, via a DNS PTR
   record, to the value "www.iab.org.".

   The resolution of protocol objects into service names is used by a
   number of applications to associate services with a particular
   protocol object.  The correct and efficient operation of these
   applications is dependent on the correct and efficient operation of
   the associated "arpa" domain name servers.

2. The "arpa" domain

   The "arpa" domain was originally established as part of the initial
   deployment of the DNS, to provide a transition mechanism from the
   Host Tables that were common in the ARPANET, as well as a home for
   the IPv4 reverse mapping domain.  During 2000, the abbreviation was
   redesignated to "Address and Routing Parameter Area" in the hope of
   reducing confusion with the earlier network name.

   The Internet Architecture Board (IAB), in cooperation with the
   Internet Corporation for Assigned Names and Numbers (ICANN), is
   currently responsible for managing the Top Level Domain (TLD) name
   "arpa".  This arrangement is documented in Appendix A.  This domain
   name provides the root of the name hierarchy of the reverse mapping
   of IP addresses to domain names.  More generally, this domain name
   undertakes a role as  a limited use domain for Internet
   infrastructure applications, by providing a name root for the mapping
   of particular protocol values to names of service entities.  This
   domain name provides a name root for the mapping of protocol values
   into lookup keys to retrieve operationally critical protocol
   infrastructure data records or objects for the Internet.

   The IAB may add other infrastructure uses to the "arpa" domain in the
   future.  Any such additions or changes will be in accordance with the
   procedures documented in Section 2.1 and Section 3 of this document.







Huston                   Best Current Practice