Editing .arpa (section)

{{Short description|Internet top-level domain}}
{{Use mdy dates|date=June 2020}}
{{Use American English|date=March 2021}}
{{Infobox top level domain
|name=.arpa
||introduced={{start date and age|1985|1|1}}
|type=Infrastructure domain
|status=Active
|registry=[[Internet Assigned Numbers Authority|IANA]]
|sponsor=[[Internet Architecture Board]]
|intendeduse=A temporary TLD to facilitate the transition from [[ARPANET]] to the DNS.
|actualuse=Internet infrastructure such as reverse DNS lookup.
|restrictions=No domain registrations possible, new subdomains rarely added
|structure=Second-level domains used for various functions related to Internet infrastructure as defined by RFCs.
|document={{IETF RFC|3172}}; {{IETF RFC|9120}}
|disputepolicy=None
|website=[https://www.iana.org/domains/arpa IANA .arpa info]
|dnssec=Yes
}}
The domain name '''arpa''' is a [[top-level domain]] (TLD) in the [[Domain Name System]] (DNS) of the [[Internet]]. It is used predominantly for the management of technical network infrastructure. Prominent among such functions are the subdomains ''in-addr.arpa'' and ''ip6.arpa'', which provide namespaces for [[reverse DNS lookup]] of [[IPv4]] and [[IPv6]] addresses, respectively.

The name originally was the [[acronym]] for the [[Advanced Research Projects Agency]] (ARPA), the funding organization in the United States that developed the [[ARPANET]], the precursor of the Internet. It was the first domain defined for the network in preparation for a hierarchical naming system for the delegation of authority, autonomy, and responsibility. It was originally intended only to serve in a temporary function for facilitating the systematic naming of the ARPANET computers. However, it became practically difficult to remove the domain after infrastructural uses had been sanctioned. As a result, the name was redefined as the [[backronym]] '''Address and Routing Parameter Area'''.

Domain-name registrations in arpa are not possible, and new subdomains are infrequently added by the [[Internet Engineering Task Force]].