Nslookup (Name System Lookup) is a tool for querying a domain name server in order to get information regarding a domain or host, and diagnosing any configuration problems that may have arisen on the DNS.
When used without any arguments, the command nslookup displays the name and IP address of the primary domain name server, as well as a command prompt for making queries. Simply type the domain name at the prompt in order to display its characteristics. You can also request information on a host by adding its name after the command nslookup:
By default, the command nslookup queries the primary domain name server installed on the machine. However, it is also possible to query a particular DNS by specifying it, preceded by a minus sign, after the command:
nslookup host.name -server.name
You can also change the query mode for nslookup by using the argument set:
To leave the command nslookup, simply type exit.