Timeouts
What if your resolver is pointing to a name server that isn’t running or a host that can’t be reached? Here’s what happens:
C:\> nslookup
DNS request timed out.
timeout was 2 seconds.
*** Can't find server name for address 192.249.249.4: Timed out
Default Server: UnKnown
Address: 192.249.249.4
>The resolver is configured to use the name server 192.249.249.4 (and only that name server). nslookup tries valiantly to contact it but times out, prints “UnKnown” for the default server, and gives you a prompt. You can’t really do anything productive without changing servers at this point—after all, no server is running at that IP address—but at least you’ve got a prompt.
Occasionally you’ll see timeouts during the course of an nslookup session. If you are looking up some remote information, the name server could fail to respond because it is still trying to look up the item and nslookup gave up waiting. How can you tell the difference between a name server that isn’t running and a name server that is running but didn’t respond? nslookup’s responses point out the difference. In this case, the response indicates no name server process is running:
C:\>nslookupDefault Server: terminator.movie.edu Address: 192.249.249.3 >movie.edu.Server: terminator.movie.edu Address: 192.249.249.3 *** terminator.movie.edu can't find movie.edu.: No response from server
The “No response from server” message is quite misleading because nslookup actually did get a response from the server. What actually ...
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Read now
Unlock full access