How to do a domain name WHOIS lookup
There are a huge number of tools available that offer a domain name whois lookup. A domain name whois service customarily offers the possibility to request the whois information of 1 or more domain names.
In cases where businesses or individuals use the domain name whois tool on a regular basis, it may be necessary to type in a "captcha". A captcha is a code that allows the website to verify that it's a person who is using the service, and not computer through automated script.
The captcha tag was introduced in whois lookups because automated services can overload the whois lookup by sending a large amount of requests simultaneously. The captcha verification allows the provider to combat any improper use of the whois service and to give priority to individual users.
An example of a whois lookup tool is domainwhoistool.com where you can simply type in the domain name and an immediate check of the domain name is performed in the whois registers.