What is RDAP?

RDAP (Registration Data Access Protocol) is the modern replacement for WHOIS. It returns domain registration data as structured JSON over HTTPS, with standardised access controls and proper support for non-Latin scripts.

WHOIS worked for forty years and showed its age in every one of them. It had no fixed response format, so every registry printed its own layout and every consumer wrote a parser per provider. It had no transport security, no authentication, and no way to show different data to different requesters — so once privacy law required contact details to be withheld, the only available answer was to redact them for everyone.

What RDAP fixes

• A defined JSON response, so one client reads every registry's answer without a bespoke parser.
• HTTPS transport, so lookups are encrypted and authenticated like any other web request.
• Differentiated access, so a verified requester with a lawful basis can receive more than an anonymous one — instead of everyone seeing the redacted view.
• Internationalisation, so names and addresses in non-Latin scripts survive the round trip.
• Bootstrap discovery: IANA publishes which server answers for which TLD, so a client can resolve any name without a hard-coded list.

What a lookup tells you

An RDAP response carries the registration and expiry dates, the current status codes, the nameservers, whether the domain is signed with DNSSEC, and the sponsoring registrar with its abuse contact. Personal details of the registrant are usually redacted, and the response says so explicitly rather than leaving you to guess.

The status codes repay learning. clientTransferProhibited means the registrar has locked the name against transfer — normal, and reversible by the owner. pendingDelete means the registration is on its way out. serverHold means the name has been removed from the zone and will not resolve at all, which is what an enforcement action looks like from the outside.

The sponsoring registrar in that record is the fastest contact point for anything specific to a registration, and it is authoritative in a way a hosting invoice is not — useful when a name was bought through a reseller.