(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.