The whois and jwhois commands allow you to retrieve a lot of information on Internet domains–likely a lot more than you might imagine. Here’s how these commands work and how they can be useful.
To get started, you probably already use nslookup to check on domain names. When you do, you’ll see output like this:
$ nslookup networkworld.com
The nslookup command queries name servers, so its output provides IP addresses for the queried domain and verifies the domain name is valid, but whois commands provide extensive details on the domain registration, domain status, responsible organizations, their locations, etc., giving you a lot more insight into domains.
Source:: Network World – Data Center