Verifying the Domain Name System function is working

Name Server Lookup (NSLookup) is a tool that is used to query the Domain Name System (DNS) server for an IP address. This verifies that the DNS server is working.

Request the host name that is associated with the loopback IP address (127.0.0.1). It should respond with the host name (localhost). You should also query specific names that are defined in the server instance that you are trying to verify. This will confirm that the specific server instance you are testing is functioning properly.

To verify DNS function with NSLookup, follow these steps:

1. At the command line, type NSLOOKUP DMNNAMSVR(n.n.n.n), where n.n.n.n is an address that you have configured the server instance you are testing to listen on.

2. At the command line, type NSLOOKUP and press Enter. This starts an NSLookup query session.

3. Type server followed by your server name and press Enter. For example: server myiseries.mycompany.com. This information displays:

     Server:  myiseries.mycompany.com   Address: n.n.n.n

   Where n.n.n.n represents your DNS server's IP address.

4. Enter 127.0.0.1 on the command line and press Enter.

   This information should display, including the loopback host name:

      > 127.0.0.1   Server:  myiseries.mycompany.com   Address:  n.n.n.n              
                                       
     
   Name:    localhost                
     Address:  127.0.0.1                                

   The DNS server is responding correctly if it returns the loopback host name: localhost.

5. Type exit and press Enter to quit the NSLOOKUP terminal session.