WHOIS (pronounced as the phrase “who is”) is a query and response protocol that is widely used for querying databases that store the registered users or assignees of an Internet resource, such as a domain name, an IP address block, or an autonomous system. WHOIS looks up the administrative contact information of a domain name from a domain name registry. WHOIS returns this information as usually text-based messages that were created when a specific domain name was registered.
WHOIS was initially designed as a way for network administrators to lookup IP addresses for troubleshooting networking problems. Later, as domain names became more commonplace, WHOIS was adapted to provide contact information for registered domains. The core query-response protocol of WHOIS is known as RFC 3912 and is a text-based protocol that queries and returns information about domain registrations.
WHOIS protocol is used today by individuals, businesses, and organizations for a variety of purposes, such as querying databases for contact information for domain registrations and looking up who owns domains. In addition, WHOIS records can also provide contact information for the technical, administrative, and billing contacts of the domain. The WHOIS protocol also provides information about domain status, such as when a domain was last modified or when it will expire.
WHOIS protocol is also used in the Internet policy and governance arena, as it is a key data source for the domain name system. WHOIS data is used to identify squatters, cybersquatters, and those engaging in illegal activities, as well as by governments to investigate cybercrime. For these reasons, WHOIS databases are often subject to access control, which can limit who can do a WHOIS lookup.
