.arpa

The domain name arpa is a

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

Purpose

Each computer using the Internet Protocol is identified by a numerical IP address for identification and location addressing.^[1] Each host is also assigned a more memorable hostname, which often relates to the purpose or ownership of the host, and is used more conveniently in user interaction with network functions, such as when connecting to or accessing a resource. Originally, the mapping between names and addresses was a cumbersome mechanical process using lookup tables distributed as computer files between network administrators. The Domain Name System (DNS) solved this inefficiency by automating the lookup function with a hierarchical naming system using domain names. When a user requests a network service using a domain name, the protocol implementation (protocol stack) translates the name to an address that can be used to reach a remote host.

This naming function, often called forward resolution, was the original purpose of the top-level domain "ARPA". It was the first domain defined in the first naming system of the nascent Internet,^[2] and was supposed to be an initial container domain for all then-existing ARPANET hosts. The next stage of development of the naming architecture foresaw the establishment of specific domains for other purposes based on certain requirements.^[2]

Reverse IP address mapping

In many applications the reverse of the name-to-address mapping is also required. The host receiving a service request may require the domain name of the originating computer, for example, to customize the service, or for verification purposes. This latter function, called Reverse DNS lookup, is implemented in the major uses of the domain arpa: its subdomains in-addr.arpa for Internet Protocol version 4, and ip6.arpa for IPv6.

Conceptually similar lookup and mapping functionality is provided by other subdomains of arpa for specific types of data.

Telephone number mapping

The domain e164.arpa provides a lookup function that retrieves information associated with

Residential networking

The domain name home.arpa was reserved by the Internet Engineering task force in May 2018 as a

With the formal development of such a hierarchical naming system, the domain also became one of the inaugural members of a set of domain names for specific types of network members, namely com for commercial users, org for organizations, edu for educational institutions, gov for government entities, and mil for networks of the United States military.^[4]

It was expected that the use of arpa would be temporary and that the existing systems would be migrated to other domains.^[4] But arpa also provided e-mail addresses associated with the Network Information Center, which administered the naming system. After serving the transitional purpose, it proved impractical to remove the domain. The domain in-addr.arpa had been installed for reverse DNS lookup of IP addresses.^[5]

Originally, the IETF intended that new infrastructure databases would be created in the top-level domain int. In May 2000, this policy was reversed and it was decided that the top-level domain int should be restricted to use by international organizations.^[6] Arpa was retained for its long-standing purpose, but its full name was changed to the Address and Routing Parameter Area, making the zone name a backronym.^[7] Registrations of internet infrastructure services in .int made prior to this policy change, were optionally grandfathered in and not required to move to .arpa.

In March 2010, zone arpa was secured with digital signatures within the Domain Name System Security Extensions (DNSSEC).^[8]

Subdomains

Subdomains of arpa are created by resolution in the work groups of the Internet Engineering Task Force via the Request for Comments process, and are maintained by the Internet Assigned Numbers Authority (IANA). The DNS zone arpa has the following subdomains:^[9][10]

References