WHOIS: The Legacy Domain Lookup Protocol
WHOIS is the legacy protocol and public directory for looking up domain registration data: registrant details, registrar, creation and expiry dates, nameservers, and status codes. It dates to the early internet and ran as plain text over port 43. For gTLDs it has been formally superseded — ICANN sunset the port-43 WHOIS requirement on January 28, 2025, making RDAP the definitive source — but the word "WHOIS" survives as shorthand for any registration-data lookup.
What WHOIS tells you (and no longer tells you)
A lookup returns the registration's vital signs: registrar, creation date, registry expiry date, EPP status codes, and nameservers. What it mostly no longer returns is the owner's identity — privacy services and post-2018 GDPR redaction mean contact fields typically show a proxy or "REDACTED FOR PRIVACY".
WHOIS vs. RDAP
RDAP delivers the same registration data as structured JSON over HTTPS, with standardized fields and proper internationalization — everything port-43 WHOIS was not. gTLD registries and registrars have offered RDAP since 2019, and since the 2025 sunset it is the authoritative gTLD channel. Many ccTLDs still run their own WHOIS services on their own terms.
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Frequently Asked Questions
Is WHOIS dead?
For gTLDs, the port-43 protocol requirement ended on January 28, 2025, and RDAP is now the definitive source. The term lives on: most "WHOIS lookup" tools today fetch RDAP data behind the scenes. Some ccTLD registries still operate traditional WHOIS.
Why does WHOIS show REDACTED FOR PRIVACY?
Privacy regulation (notably GDPR) and registrar privacy services led registries and registrars to redact personal contact data from public output. The registrar still holds the real registrant data.