.arpa
| Manager: | IANA |
| Registry Provider: | .ARPA Registry |
| Date Implemented: | 1985 |
| Type: | TLD |
| Community: | for Internet-infrastructure purposes only |
More information: 
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.arpa stands for Address and Routing Parameter Area. It is one of the original top level domain names (TLDs) delegated in the root zone of the Domain Name System (DNS) of the Internet. It is classified as an infrastructure top-level domain name and it is exclusively used to support operationally-critical infrastructural identifier spaces. The Internet Architecture Board (IAB) and ICANN jointly manage the .arpa TLD. The Internet Assigned Numbers Authority (IANA) is in-charge of the operational administration of the TLD with the cooperation of the technical community. Technical guidelines are provided by the IAB.[1] [2]
Originally, .arpa was established as a temporary domain to serve as a transition mechanism for a set of host names in the ARPANET that were administered by DARPA. The host names were to be phased out after a replacement was created under the categorized TLDs which include .com, .edu, .mil, .net, .gov and .org.[3] Although the initial plan for .arpa was to purge everything after the transition, the sub-domain in-addr.arpa remained active and it has been utilized for reverse DNS queries of Internet Protocol addresses.[4]
In 2000, the IAB informed the technical community that .arpa had been re-designated as an Address and Routing Parameter Area. .arpa is to serve as a domain space where all new infrastructure sub-domains will be placed to maintain the stability of the internet. The IAB also recommended to the Internet Engineering Steering Group (IESG) that no new infrastructure domains were to be added to .int, that protocols requiring specific domain roots should be rooted elsewhere, and that new infrastructure domains from the Internet Engineering Task Force (IETF) protocols must be allocated to the .arpa TLD. Management is to be handled by IANA. In addition. the IAB also suggested the review of all existing IETF infrastructures allocated under .int, and if the costs of transferring them is greater than the risk of staying in place. [5]
Uses for .arpa
IANA has allowed the following sub-domains on .arpa:[6]
- E164.ARPA - mapping E.164 numbers to Internet URIs
- IN-ADDR-SERVERS.ARPA- hosting authoritative name servers for the in-addr.arpa domain
- IN-ADDR.ARPA- mapping IPv4 addresses to Internet domain names
- IP6-SERVERS.ARPA- hosting authoritative name servers for the ip6.arpa domain
- IP6.ARPA- mapping IPv6 addresses to Internet domain names
- IRIS.ARPA- locating Internet Registry Information Services
- URI.ARPA- resolving Uniform Resource Identifiers (URI) according to the Dynamic Delegation Discovery System
- URN.ARPA- resolving Uniform Resource Names (URN) according to the Dynamic Delegation Discovery System