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The American Registry for Internet Numbers (ARIN) is a nonprofit, member-based Regional Internet Registry (RIR). It manages and registers IPv4 and IPv6 addresses and Autonomous System Numbers (ASNs) in its service region. It does not provide the Internet connection to your home or device; that is the role of an internet service provider.
What does ARIN stand for?
ARIN stands for the American Registry for Internet Numbers. Established in December 1997, it is one of five Regional Internet Registries that coordinate Internet number resources and related registration records around the world. ARIN’s introduction describes its organization and service region.
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What does ARIN do?
ARIN administers Internet number resources in its region. Its work includes allocating, assigning, and transferring address space and ASNs, as well as maintaining resource records. These identifiers are important to Internet operations, but ARIN’s role is administrative: it is not a carrier, does not route your household traffic, and does not sell you Internet access.
It manages addresses and ASNs
IPv4 and IPv6 addresses identify network interfaces and endpoints for Internet communication. An ASN identifies a network for routing purposes. ARIN registers these resources and records information about the organizations to which they are associated. Its registry services include resource management and related operational tools.
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It supports routing-related services
ARIN’s services include the Internet Routing Registry, Resource Public Key Infrastructure (RPKI), reverse DNS, and resource-record management. These services support network operators and the broader operation of the Internet; they are distinct from the access service an ISP provides to an individual customer. ARIN’s registry services page describes these offerings.
It coordinates policy and outreach
ARIN also coordinates community-driven policy development for managing Internet Protocol number resources and provides informational outreach. Its mission statement says it supports Internet operations through number-resource management, coordinates policy development by the community, and advances the Internet through outreach. ARIN’s introductory page presents the mission statement.
Where does ARIN operate?
ARIN’s service region covers the United States, Canada, and many Caribbean and North Atlantic countries. It is one of five RIRs; the registries divide responsibility for number-resource management and related records across the global Internet community. ARIN’s region should not be confused with a claim that it administers resources everywhere. ARIN’s overview identifies its service area, and the Number Resource Organization provides context on the RIR system.
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What information can an ARIN lookup show?
ARIN provides public registration information through Whois and RDAP. A lookup can show records associated with an IP resource or ASN, including the organization and Points of Contact recorded for it. ARIN also continues to support its Whois-RWS interface. Use ARIN RDAP or Whois-RWS to search registry records.
A registry record is not proof of which person used an IP address at a particular time. It describes registered resources and associated organizations or contacts, not a verified identity for every user or device. ARIN says additional operational information it collects is generally not public; a public lookup should not be treated as a complete record of network activity. ARIN’s Whois information explains its public registration-data services.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.How large is ARIN?
ARIN’s 2024 annual report said it served approximately 40,000 organizations and maintained roughly 8 million registration records. Those are figures reported for 2024, not live counts. ARIN’s 2024 annual report provides the dated figures.
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