A type of Domain Name System (DNS) resource record that identifies the specific host as a name server. For each zone governing a portion of the DNS namespace, there should be one name server (NS) record for each name server in the zone. Each NS record also requires an associated address record that resolves the host name of the name server into its IP address. The syntax for the NS record is specified in Request for Comments (RFC) 1035.
Here is an example of an NS record:
microsoft.com. IN NS nameserver2.microsoft.com.
In this example, the domain microsoft.com is within the zone of authority of the name server named nameserver2. IN stands for Internet, and NS stands for name server.