Asia Pacific Network Information Centre American Registry for Internet Numbers The Registration Data Access Protocol (RDAP) is used by Internet Number Resource (INR) registries and domain name registries to provide access to their resource registration information. The core specifications for RDAP define basic search functionality, but there are various IP and ASN-related search options provided by INR registries via their Whois services for which there is no corresponding RDAP functionality. This document extends RDAP to support those search options.