RDAP

RDAP is the Registration Data Access Protocol: a JSON web API that returns who registered a domain and when, replacing WHOIS.

RDAP is the Registration Data Access Protocol. It is a JSON web API that returns the registration record for a domain: when it was created, when it expires, which registrar holds it, and what status codes apply.

A query is an ordinary HTTPS GET:

GET https://rdap.verisign.com/com/v1/domain/stripe.com
Accept: application/rdap+json

The answer is JSON with a defined schema, so a client reads a field instead of parsing a paragraph. That is the entire difference from WHOIS, and it is why the industry moved.

What Domduck records

The rdap source, read once rather than daily, because a registration date does not change. It stores the creation date, the registrar name and the status codes, and the domain age on any page is computed from that date rather than stored as a number that would be wrong tomorrow.

Domduck resolves the right server through bootstrap rather than through a redirect service, and it honors rate limits by reading each domain once instead of on every page view.

Why it matters

Registration date is the most durable fact about a domain. Ratings move, certificates rotate, DNS changes, and the creation date stays the same for the life of the name. It is also the field most often quoted wrongly, because many tools still read a WHOIS text blob and pick the wrong line on registries that format it differently.

Two cautions. RDAP fields are redacted under privacy rules, so registrant name and email are usually absent, and that is the rule rather than a failure. And coverage is not complete: generic top-level domains are required to serve RDAP, while a large share of country top-level domains still do not.

Related

  • WHOISWHOIS is the 1980s text protocol on port 43 that returned domain registration details, now replaced by RDAP for generic top-level domains.
  • RDAP vs WHOISRDAP returns structured JSON over HTTPS with a defined schema. WHOIS returned free text over port 43 in whatever shape each registry chose.
  • RDAP bootstrapRDAP bootstrap is how a client finds the right server for a domain: fetch IANA’s registry, match the top-level domain, get the base URL.
  • Domain status codesDomain status codes are the EPP labels a registry returns for a name, such as clientTransferProhibited or pendingDelete, that say what may happen to it next.

Primary source: ICANN on RDAP