Looking up records in network information centers (NICs) using WHOIS

The WHOIS protocol and the WHOIS servers are used to store and retrieve information about registrants and assignees of internet ressources, such as domains and addresses.

There are a number of different WHOIS servers. Five WHOIS servers covers regional areas of the world. Other cover specific interests. Well known WHOIS servers are some of the following.

• The American Registry of Internet Numbers (ARIN), that covers United States of America (USA).
• The Asia/Pacific Network Information Center (APNIC), that covers East Asia, Australia, New Zealand and the Pacific islands.
• The Réseaux IP Européens Network Coordination Centre (RIPE NCC), that covers Europe.
• The Network Abuse Clearing House, that covers contacts for network abuse.
• The Network Solutions Registry for Internet Numbers, that covers.com, .net, .org and more.

WHOIS client software, such as open source command line utilities, can use a subdomain system to construct the name of a WHOIS server to use from the top level domain (TLD) of the supplied argument. As an example of this, the built in command line utility of the FreeBSD operating system would give the same result with the following arguments.

whois opentech.dk
whois -h dk.whois-servers.net opentech.dk


Such lookup is also referred to as a WHOIS query.

The information in WHOIS servers is maintained by regional internet registries (RIRs), such as DK Hostmaster and Network Solutions.