What Is an ARIN Lookup?

An ARIN lookup refers to the process of querying the American Registry for Internet Numbers (ARIN) database to obtain information about IP address allocations and assignments. ARIN is one of the Regional Internet Registries (RIRs) responsible for managing the distribution of IP address resources in North America, including the United States, Canada, and parts of the Caribbean.

Here's what you can typically find through an ARIN lookup:

1. IP Address Information: You can find details about the allocation and assignment of IPv4 and IPv6 addresses. This may include the range of IP addresses, the organization or entity to which they are allocated or assigned, and contact information.

2. Organization Information: ARIN maintains records of organizations that have been allocated IP address blocks. You can look up an organization by its name or IP address and find information about its address, contact details, and the IP resources it holds.

3. ASN (Autonomous System Number) Information: ARIN also manages the assignment of ASNs, which are used for routing on the internet. You can look up ASNs to find information about the organization that holds them.

4. IP Address Blocks: ARIN assigns IP address blocks to organizations based on their needs. You can find information about which IP blocks are reserved, allocated, or available for assignment.

5. Reverse DNS Delegation: ARIN maintains records for reverse DNS (Domain Name System) delegation. Reverse DNS maps IP addresses to domain names. You can look up information about reverse DNS assignments for IP address blocks.

ARIN lookups are valuable for network administrators, internet service providers (ISPs), and organizations to manage their IP address resources effectively, troubleshoot network issues, and identify the entities responsible for specific IP addresses or ASNs. ARIN provides online tools and a public database (Whois) that allows users to perform these lookups.