WHOIS Protocol
A query and response protocol widely used for querying databases that store the registered users or assignees of an Internet resource, such as a domain name or an IP address block. Traditionally operates over TCP port 43.
Educational Reference
WHOIS & Domain Term Glossary
Confused by registry jargon? Browse our dictionary of standard industry terms to understand how domain databases, crawlers, and registrar records operate.
Core Protocols
RDAP (Registration Data Access Protocol)
The modern successor to the WHOIS protocol. RDAP delivers domain registration data in standardized JSON format over secure HTTP (HTTPS), allowing for better localization, structured queries, and secure access controls.
Port 43 WHOIS
The default TCP port designated for raw WHOIS text queries. Modern crawlers and clients connect to port 43 of registry or registrar servers to fetch plain-text WHOIS data records.
Domain Entities
Registrant
The individual or corporate entity that holds the rights to use a domain name. This is the domain 'owner' listed in the WHOIS contact blocks.
Registrar
An accredited organization (like GoDaddy, Namecheap, or Cloudflare) authorized to sell domain registrations to the public and write database records directly to the registry.
Registry
The master database operator responsible for managing all domain registrations under a specific Top-Level Domain (TLD). For example, Verisign is the registry operator for Verisign's .com and .net extensions.
IANA ID (Internet Assigned Numbers Authority ID)
A unique numeric identifier assigned to ICANN-accredited registrars. Using IANA IDs allows database systems to track registrars independently of name spelling changes.
Privacy & Compliance
GDPR Redaction
The masking of personal contact details (names, emails, phones) in public WHOIS outputs to comply with the European Union's General Data Protection Regulation. Redacted fields are usually replaced with terms like 'Redacted for Privacy'.
Privacy / Proxy Shield
A commercial service offered by registrars (e.g. WhoisGuard, Domains By Proxy) that replaces the registrant's private contact details with secondary forwarding details to prevent spam harvesting.
Technical Settings
Nameservers (DNS)
The servers that point a domain name to specific web servers or mail servers. Valid WHOIS records always list the active nameservers associated with a registered domain.
Domain Lifecycle Dates
The three critical timestamps inside a WHOIS database record: Creation Date (when the domain was registered), Update Date (when it was last modified), and Expiration Date (when it will return to the open market if unpaid).
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Our databases parse and normalize all of these fields into standard columns, making database queries simple.
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