WHOIS and RDAP (Domain Registration Data)

WHOIS is the long-standing protocol for querying domain registration data, using plain text over port 43. RDAP (Registration Data Access Protocol) is its successor: it returns structured JSON over HTTPS and supports authentication, standard error codes and redirects between registries.

Why it matters

These lookups tell you the registrar, creation and expiry dates, status codes and delegated nameservers, which is useful for checking a domain's age, confirming it has not lapsed, or investigating abuse. ICANN has made RDAP the authoritative source for generic top-level domains, so tools increasingly query it first. Since privacy regulation, personal contact details are usually redacted, so expect to see "REDACTED FOR PRIVACY" for registrant fields.

Example

$ curl -sL https://rdap.org/domain/example.com | jq -c '.events[] | select(.eventAction=="registration")'
{"eventAction":"registration","eventDate":"1995-08-14T04:00:00Z"}

The rdap.org service redirects your query to the correct registry. Classic WHOIS: whois example.com.

Common mistakes

• Expecting to find the owner's name and email. They are normally redacted.
• Parsing WHOIS text with regular expressions. Formats differ per registry; RDAP's JSON is more reliable.
• Treating the expiry date as exact for planning, when grace and redemption periods follow it.
• Forgetting that some country-code TLDs run their own rules or lack RDAP.

Related

• Registrar
• Nameserver
• NS record
• Guide: Domain expiry grace and redemption
• Tool: WHOIS lookup

This page is general information written by our editorial team and updated when documentation changes. Servers and providers differ, so test changes safely first. See our editorial policy and disclaimer.