Glossary

WHOIS

WHOIS is a query protocol that returns registration details for a domain or IP, such as the registrar, nameservers, and creation date.

WHOIS is a long-standing query/response protocol that returns registration information about a domain name or ip-address — who registered it, through which registrar, when, and which nameserver hosts it uses.

What you can learn

Registrar and registration/expiry dates.
Authoritative nameservers.
For IPs: the owning organisation and asn.
Contact details, though these are now usually redacted for privacy.

Limitations

Since GDPR and ICANN privacy rules, most personal contact data is masked behind privacy services. WHOIS output is also free-form text that varies by registry, making it awkward to parse reliably — which is why the structured successor, rdap, is increasingly preferred.

Why it matters for hosting

A WHOIS lookup is the quickest way to confirm a domain's registrar, check when it expires, and discover which nameservers control its dns.

See also

RDAP (Registration Data Access Protocol) RDAP is the modern, structured successor to WHOIS, returning domain and IP registration data as JSON over HTTPS with standardized fields. Nameserver A nameserver is a server that answers DNS queries for a domain, storing its zone records and telling the internet where the domain points. IP Address An IP address is the unique numeric label assigned to each device on a network, used to route data to the right destination across the internet. ASN (Autonomous System Number) An ASN is a unique number identifying a network of IP ranges under one operator, used by BGP to route traffic across the internet.

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