WHOIS servers by TLD, with RDAP

How WHOIS servers are organized

ICANN's glossary explains that the WHOIS system has long been based on "a simple plain text-based protocol (called the WHOIS protocol), described in the RFC 3912." RFC 3912 itself says: "A WHOIS server listens on TCP port 43 for requests from WHOIS clients." There is no single global WHOIS server. Each TLD registry can run its own, and IANA records it in the TLD's delegation record under "WHOIS Server". The .com record, for example, names whois.verisign-grs.com.

IANA also runs a WHOIS service for the top level itself. A query for com sent to whois.iana.org on port 43 returned a record headed "% IANA WHOIS server" with the line whois: whois.verisign-grs.com, so IANA's server tells you where to ask next. The .arpa infrastructure domain uses whois.iana.org as its own WHOIS server.

RDAP works differently. ICANN's RDAP page says: "The Registration Data Access Protocol (RDAP) enables users to access current registration data and was created as the replacement for the WHOIS protocol." It runs over HTTP, and instead of port 43 a client reads IANA's RDAP bootstrap file, the method defined in RFC 9224, to find the base URL for a TLD. The copy used here was published on 2026-09-16.

What changed for generic TLDs in 2025

ICANN's RDAP page states: "All gTLD registries and registrars are required to provide RDAP services using the gTLD RDAP Profile, but as of 28 January 2025 they are no longer required to provide WHOIS services (except for .com, .name, and .post)." The IANA data shows the result. All 1,111 generic TLDs have an RDAP server in the bootstrap file, but only 623 still list a WHOIS server; 488 are RDAP only. .app, for example, lists no WHOIS server at all. The three exceptions ICANN names still list one: .com (whois.verisign-grs.com), .name (whois.nic.name) and .post (whois.nic.post).

Country codes follow their own rules

The ICANN rule covers generic TLDs only, and the 309 country codes look very different. 236 of them list a WHOIS server at IANA, but only 76 have an RDAP server in the bootstrap file. 163 offer WHOIS only, 73 offer both, and 70 have neither. Just 3 country codes, .na, .pn and .uk, are RDAP only. .io (whois.nic.io), .de (whois.denic.de) and .us (whois.nic.us) list a WHOIS server but no RDAP. When a country code has neither, the lookup above shows the registry website from its IANA record instead, where the record lists one (58 of 70 do).

Shared servers and naming patterns

The 873 WHOIS entries point to 778 different host names. 659 TLDs follow the pattern whois.nic.<tld>. The most shared hosts are whois.nixiregistry.in (16 TLDs), whois.registry.click (14 TLDs), whois.nic.gmo (12 TLDs) and whois.gtld.zdns.cn (10 TLDs). RDAP is far more concentrated: the 1,202 TLDs with RDAP use 591 base URLs, and https://rdap.identitydigital.services/rdap/ alone serves 451 of them, ahead of https://pubapi.registry.google/rdap/ (46) and https://rdap.gmoregistry.net/rdap/ (46).

How to query WHOIS and RDAP yourself

The common whois command-line client takes a server with -h. RFC 3912 adds that "All requests are terminated with ASCII CR and then ASCII LF", so a raw query with netcat needs that line ending. For RDAP, RFC 9082 defines the path "domain/<domain name>" under the base URL from the bootstrap file.

whois -h whois.verisign-grs.com example.com
whois -h whois.iana.org io
printf 'example.com\r\n' | nc whois.verisign-grs.com 43
curl https://rdap.verisign.com/com/v1/domain/example.com

The second line asks IANA which server handles a TLD; the third sends the same query by hand; the last one fetches the RDAP record.

Sources and method

• IANA Root Zone Database: WHOIS server and registration URL from each TLD delegation record, fetched September 25, 2026 between 19:35 and 19:55 UTC.
• IANA RDAP bootstrap file for DNS, publication 2026-09-16T19:00:03Z, fetched September 25, 2026.
• IANA WHOIS Service and a port 43 query to whois.iana.org for "com", saved September 25, 2026.
• ICANN: Registration Data Access Protocol (the 28 January 2025 change).
• ICANN glossary: WHOIS and RDAP.
• RFC 3912 (WHOIS), RFC 9224 (RDAP bootstrap), RFC 9082 (RDAP query format).
• Method: every count is computed by script from the saved files. Trailing slashes aside, the RDAP URLs on the IANA delegation records and in the bootstrap file match for every TLD.