Theoretically, anyone can identify a domain name registrant by searching the Whois protocol. A standard Whois search will provide anyone querying the public Whois database with information regarding a domain name. You can retrieve key data about a domain like ownership, availability, registration and expiration details.
There are different ways to implement a whois search. Traditionally, a command line interface application was used, by nowadays, web based tools are widely use, and have simplified the process.
Web-based Whois queries
ICANN has made Whois look-ups as easy as possible these days. To perform a search, users only need to go to one of many web based Whois lookup tools, enter a domain name, and click "Lookup."
Command line Whois Queries
It’s possible to override third party services and perform a Whois query from your own computer, if you use a supporting operating system, you can use the Windows command prompt, or Linux’s lookup command, for example.
Search via a registrar
There are a few domain extensions where the record needs to be checked on the specific domain’s Whois server to perform a search. At the time of writing, there’s no standardized method for finding out the responsible Whois server for a given domain extension. This means these types of Whois lookups require extra work, like performing a search through the domain name's registrar to retrieve the details of ownership.
Whois IP Queries
It’s also possible to discover who controls an IP address. So-called IP lookups are browser-based tools used for discovering the contact data and IP geolocation for the owner of the address being queried. To perform an IP lookup, you just need to type the IP address into the IP lookup search box. If the owner doesn’t use WhoisGuard, the results will be displayed.