Whois
From WebHost Wiki
WHOIS is a TCP-based query/response protocol used for querying a database to be able to get the details of a domain name registrant or IP address. It's also a simple way of checking to see if a domain name is available.
If you have SSH access or are running a Linux based system then you can use the command line whois tool.
Open terminal and type the command: - whois [domainname] eg: whois webhost-wiki.com
To perform a whois without access to the following tools, you can use a whois website such as the one offered on the domaintools website:
http://whois.domaintools.com/
