DNS on Windows Server 2003, 3rd Edition

Switching Servers

Sometimes you want to query another name server directly—for example, if you think it is misbehaving. You can switch servers with nslookup by using the server or lserver commands. The difference between server and lserver is that lserver queries your “local” server—the one you started out with—to get the address of the server you want to switch to; server uses the default server instead of the local server. This difference is important because the server that you just switched to may not be responding, as we’ll show in this example:

C:\> nslookup 
Default Server:  relay.hp.com 
Address:  15.255.152.2

When we start up, our first server, relay.hp.com, becomes our lserver (this will matter later on in this session):

> server galt.cs.purdue.edu. 
Default Server:  galt.cs.purdue.edu 
Address:  128.10.2.39 

> cs.purdue.edu. 
Server:  galt.cs.purdue.edu 
Address:  128.10.2.39 

*** galt.cs.purdue.edu can't find cs.purdue.edu: No response from server

At this point we try to switch back to our original name server. But there is no name server running on galt to look up relay’s address:

> server relay.hp.com. 
*** Can't find address for server relay.hp.com: No response from server

Instead of being stuck, though, we use the lserver command to have our local server look up relay’s address:

> lserver relay.hp.com. 
Default Server:  relay.hp.com 
Address:  15.255.152.2 

>

Since the server on galt did not respond—it’s not even running a name server—it wasn’t possible to look up the address of relay ...