The state of RDAP
1,245
top-level domains answer RDAP queries
How a lookup gets answered
- 1,245top-level domainsEvery TLD with an RDAP service we can reach.
each one is answered by
406registry serversOne server usually answers for many TLDs — 6 of them carry 60%.a thin registry answers with a referral to
409registrar 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.
45
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 406 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 406 registry servers we resolve have a certificate fault
3 unreachable2 incomplete chain1 no tls at all1 name mismatch1 expired
88.4% reachable over IPv6
8.8%
of the 409 registrar servers we resolve have a certificate fault
15 unreachable13 expired6 incomplete chain2 name mismatch
69.1% 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
15%
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.
We resolve every TLD above, including the ones IANA does not list.