RDAP

RDAP (Registration Data Access Protocol) is the IETF-standardized successor to WHOIS for looking up who registered a domain or IP address block. Unlike WHOIS’s loosely defined, plain-text, per-registry output formats, RDAP returns structured JSON over HTTPS with a consistent schema across registries — the status, event-action and entity-role values a response can use are themselves standardized in IANA’s RDAP JSON Values registry — making it far easier for software to parse reliably and supporting features WHOIS lacked, like internationalization and differentiated access levels for redacted personal data under privacy rules like GDPR. ARIN’s RDAP documentation draws the same contrast: RDAP is an HTTP-based REST-style protocol with standardized JSON responses, whereas WHOIS is a text-based protocol with its own port. Most domain and IP registries now run RDAP services alongside legacy WHOIS, and RDAP is gradually becoming the primary lookup method as WHOIS is phased down — a transition ICANN has required of gTLD registries and registrars since 2019; many RDAP responses also label a domain’s registrar-mandated abuse contact as a distinct entity, the starting point before filing an abuse report from a WHOIS/RDAP result. RDAP’s query format and JSON response structure are defined in RFC 9082 and RFC 9083.

RDAP is part of AdminKit’s DNS cluster; the full AdminKit glossary lists other related terms.