The state of RDAP
1,249
top-level domains answer RDAP queries
How a lookup gets answered
- 1,249top-level domainsEvery TLD with an RDAP service we can reach.
each one is answered by
407registry serversOne server usually answers for many TLDs — 6 of them carry 60%.a thin registry answers with a referral to
415registrar servers, so farWhere the fuller record sits. We only learn one by being referred to it, so this is a floor that rises as we see more domains — not a census.
46
of those TLDs run stealth RDAP servers
IANA's bootstrap file is what every RDAP client reads to find a registry. These services work and are not in it, so a client that trusts the file alone reports them as unsupported — that is stealth RDAP.
A few registry servers carry most of it
60%
of every RDAP-resolvable TLD is answered by just 6 of those 407 registry servers.
Each block is one registry server, sized by the number of TLDs it answers for. A hostname is not necessarily one machine — it may front a pool, and separate hostnames may share a backend — so read this as a floor on how concentrated RDAP is, not a machine count.
Registries keep their servers; registrars less so
2%
of the 407 registry servers we resolve have a certificate fault
6 unreachable1 no tls at all1 incomplete chain
91.2% reachable over IPv6
11.8%
of the 415 registrar servers we resolve have a certificate fault
20 expired16 unreachable9 incomplete chain4 name mismatch
72.5% reachable over IPv6
One dot per server. The registry side is close to every registry running RDAP; the registrar side is only those we have been referred to, so it grows as we see more domains.
What a client can rely on
16%
say what they redacted
RFC 9537 lets a server name each field it withheld. Without it, an empty registrant email could mean the contact has none or that the registry removed it — and nothing in the response tells you which.
Which RDAP server answers for each TLD is listed in the TLD directory, along with which fields that server actually returns.
One API for every TLD
We resolve every TLD above, including the ones IANA does not list.