Finding Out a Host’s Aliases
One thing you can’t easily do with nslookup—or any query tool, for that matter—is find out a host’s aliases. With the host table, it’s easy to find both the canonical name of a host and any aliases. No matter which you look up, they’re all there together on the same line, as shown in the following excerpt from HOSTS:
192.249.249.3 terminator.movie.edu terminator bigt
With DNS, however, if you look up the canonical name, all you get is the canonical name. There’s no easy way for the name server or the application to know whether aliases exist for that canonical name:
C:\>nslookup
Default Server: wormhole.movie.edu Address: 192.249.249.1 >terminator
Server: wormhole.movie.edu Address: 192.249.249.1 Name: terminator.movie.edu Address: 192.249.249.3
If you use nslookup to look up an alias, you’ll see that alias and the canonical name. nslookup reports both the alias and the canonical name in the packet. But you won’t see any other aliases that might point to that canonical name:
C:\>nslookup
Default Server: wormhole.movie.edu Address: 192.249.249.1 >bigt
Server: wormhole.movie.edu Address: 192.249.249.1 Name: terminator.movie.edu Address: 192.249.249.3 Aliases: bigt.movie.edu
You can find out all the CNAMEs for a host in a particular zone by transferring the whole zone and picking out the CNAME records in which that host is the canonical name. You can have nslookup filter on CNAME records:
C:\> nslookup
Default Server: wormhole.movie.edu Address: ...
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