Nslookup (name server lookup) is a command line tool for querying the domain name system (DNS) servers. It basically query a server on the internet to get a mapping between a given host name and its related IP address. It can also perform reverse lookup (ie: find the name with a given IP address) but reverse records are not mandatory and may not be found within the DNS. The Internet Systems Consortium has deprecated nslookup in favor of dig. However, nslookup is still widely used by network administrators mainly because of its simplicity. dns lookup online, online dns ip lookup
What is a domain name?
A text name which a computer network registers. The domain name is used to give computers text names rather than using the numeric IP addresses. This like getting a vanity phone number that spells out a word to make it easy to remember. Example domain name: google.com
Choose the DNS server to use for the DNS lookup function. This can be used to query a specific nameserver. This is convenient to see if each of your nameservers has the proper configuration for the domain entered. This setting does not affect the DNS server used by the Lookup and Traceroute functions.