Check who owns a domain, when it was registered, when it expires and which nameservers it is using.
How this lookup works
It queries RDAP first — the JSON-based successor to WHOIS, which returns clean structured fields rather than a wall of text. Where a registry has not published RDAP yet, it falls back to the classic WHOIS protocol on port 43 and follows the registry referral, then extracts the useful fields from the response.
That fallback matters more than you would expect: coverage across country-code domains is still uneven, and a tool that only speaks RDAP will simply return nothing for a large slice of the internet.
What is worth checking
- Expiry date. The single most expensive thing to miss. A domain that lapses can be picked up by someone else within hours.
- Registrar. You need to know who to log in to. If the registrar is unfamiliar and you did not choose it, treat that as a problem worth investigating.
- Status flags. Watch for
clientHoldorserverHold, which both mean the domain is suspended and will not resolve — regardless of what DNS says. - Nameservers. These tell you which DNS provider is actually serving the zone. A common support case is a client editing records at an old provider whose nameservers are no longer in use.
Before you take on a client’s domain
If you are about to host someone’s site, run this first and write down the registrar and expiry date. It is far easier to ask a client for registrar access in week one than it is to explain in six months that the domain has expired and nobody can recover it.
Many domains now redact the registrant’s personal details by default, particularly in the EU and UK where GDPR applies. That is expected, and it is not a sign that something is wrong.