What is nslookup?

Introduction to nslookup

Nslookup (Name System Look Up) is a tool for querying a name server to obtain information about domain or a host and this diagnose possible DNS configuration problems.Invoked without arguments, the nslookup displays the name and IP address of primary name server and displays a command prompt for the query. Simple type a domain at the prompt to display its characteristics. It is also possible to request information about a host by specifying its name after the nslookup command:

Nslookup host.name

By default, the nslookup command queries are primary name server configured on the machine. It is however possible to query a specific name server by specifying it after the command preceded by a "–"sign:

Nslookup host.name -server.name

You can change the query mode of the nslookup command with the set clause:

• Set type = mx collects information about a domain's mail server (s).
• Set type = ns collects information about the domain name server associated with the domain
• Set type = a collects information about a host on the network. This is the default polling mode.
• Set type = soa is used to display the information in the Start of Authority (SOA) field.
• Set type = cname is used to display information about aliases.
• Set type = hinfo will display information about the hardware and operating system of the host when these data are populated.