Introduction to nslookup

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:

nslookup host.name

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:

• set type=mx is used for getting information regarding a domain's mail server(s).
• set type=ns is used for getting information regarding the domain's name servers.
• set type=a is used for getting information regarding a network host. It is the default query mode.
• set type=soa is used for displaying information in the SOA (Start Of Authority) field.
• set type=cname is used for displaying information regarding aliases.
• set type=hinfo is used for displaying information regarding the host's hardware and operating system, if this data has been made available.