nslookup has two modes namely interactive mode and non-interactive mode. In interactive mode, the user can query the name servers for host or domain info. It also displays the list of host available for a domain. In this the command can be interrupted in the middle using “ctrl+C” and to exit from the file either exit or “ctrl+D” has to be typed. In non-interactive mode, it just displays only the name and the requested info. If the request was unsuccessful then it sends an error report to the terminal. The error may be due to server failure, connection timed out issues, unreachable networks, no records or response from the server.