IRR Overview

Understanding Internet Routing Registries

Internet Routing Registries (IRRs) contain information — submitted and maintained by ISPs or other entities — about Autonomous System Numbers (ASNs) and routing IP number prefixes. IRRs can be used by ISPs to develop routing plans. For example, ISPs who use Border Gateway Protocol (BGP) can create Access Control Lists to permit or deny traffic in their networks based on route registry information.

The global IRR is comprised of a network of distributed databases maintained by Regional Internet Registries (RIRs) such as ARIN, service providers, and third parties. Some of these databases contain only routing information for a particular region, network, or ISP. Other IRR databases mirror specific IRR databases, and contain IRR information from multiple databases. One of the IRR maintainers provides a list of routing registries.

A world map illustrating connections between the five Regional Internet Registries and other Internet Routing Registries

Overview of the ARIN IRR

As part of the global IRR, the ARIN IRR provides a registry of Internet routing objects for resources in the ARIN region.

An illustration of how information flows through Internet Routing Registries

The ARIN IRR stores information in Routing Policy Specification Language (RPSL) objects. These objects are submitted to the ARIN IRR by resource holders such as ISPs and retrieved by other IRRs when ISPs in their region are requesting ARIN routing information.

ARIN’s IRR is integrated with ARIN Online. The IRR-email and IRR-online systems are both connected to ARIN’s IRR database. The database provides IRR information via a Near Real-Time Monitoring (NRTM) service and FTP, and is also accessible using Whois on port 43.

An illustration of the ARIN IRR system updated June 2020

More information on how to submit and retrieve IRR data is available at ARIN’s Internet Routing Registry (IRR) page.

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