The TLDs We Still Can't Check With RDAP (and How You Can Help)

When DNSLister says a domain is available, we want to be sure. The best tool for that is RDAP, the Registration Data Access Protocol. It's the modern, machine-readable replacement for WHOIS: you ask the registry about a name, and it answers in clean JSON with "registered" or "not found".

There's one catch: you have to know which server to ask.

How RDAP servers are found

IANA, the organization that runs the root of the domain system, publishes an official RDAP bootstrap file at data.iana.org/rdap/dns.json. It's a simple map: these TLDs, ask this server. Every RDAP client, including ours, starts there.

As of IANA's 2026-09-30 edition, the file lists RDAP servers for about 1,200 TLDs. Almost every generic TLD is covered (.com, .net, .org, .app, .shop and the rest), because ICANN requires RDAP for them.

Country-code TLDs (ccTLDs) are a different story. They're run by national registries that set their own rules, and many haven't published an RDAP server to IANA.

The big names missing from IANA's list

Here are well-known TLDs with no RDAP server in IANA's bootstrap file as of that edition:

Region	TLDs
Europe	.de, .eu, .it, .es, .ch, .at, .be, .dk, .se, .pt, .ie, .lu, .hu, .ro, .gr, .sk, .ru, .by, .tr, .me, .gg
Asia-Pacific	.jp, .cn, .hk, .my, .vn, .ph, .nz, .kz, .la, .ws
Americas	.us, .mx, .co, .cl
Africa / Middle East	.za, .il, .ir, .so
Popular "tech" ccTLDs	.io
Special	.edu

Some of these registries do run an RDAP server; they just haven't listed it with IANA. Others only offer WHOIS, or nothing public at all.

What we do instead

When there's no RDAP server, we don't give up on the TLD:

1. WHOIS fallback. For many of these (.de, .it, .jp, .eu, .io and others) we ask the registry's WHOIS server instead. It works, but WHOIS is plain text that varies by registry and is more heavily rate-limited.
2. DNS check. If a name has nameservers, it's registered. That catches most taken names quickly. But a name with no nameservers isn't necessarily free: it may be registered and simply not set up. (We found this a lot with .si.)
3. We say so. When a result rests on weaker evidence, we'd rather show you that than pretend to be sure.

Help us find the missing endpoints

This is where we'd love help from registry staff, registrars, and anyone who's dug into this before:

• Do you know an RDAP server for one of the TLDs above? Even an unofficial or undocumented one. We'll test it before relying on it.
• Does your registry have RDAP "coming soon"? We'll add it the day it goes live.
• Seen a working WHOIS server for a ccTLD we don't support? That helps too.

Send it to us here. The subject line is already filled in. Just paste the URL and the TLDs it covers.

We'll keep this page updated as the list gets shorter.

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Curious how healthy each TLD's lookups are right now? See TLD Health.