One of the first problems people encounter when they are new to DNS is where to start looking when they need to make a DNS change. Say you want to add a new subdomain for a piece of server software you are trying out, but where exactly do you add that new A record the instructions keep talking about?
The Whois command is used to collect information about a domain including who owns the domain, basic contact information for the domain owner, and the nameservers that the domain is using.
Many times when a website is “down,” it is unable to be found by DNS. If you are trying to troubleshoot DNS errors, or trying to understand a DNS error you have encountered, this is right where you should be.