Link to home
Start Free TrialLog in
Avatar of concordit

asked on

NSLOOKUP will not work unless I add in a trailing period...

I am having an issue with dns lookups. The setup it a bit complex, so I will explain here briefly. We have a product called "Campus Manager", it basically switches around client machines to different VLANS based on if you have antivirus and MS updates installed. The two VLANS where users are placed initially are for registration and remediation. The "Campus Manager" box is a linux box with their application running on it. Its has a standard dhcpd and named install on it to service the two VLANS. The named config will only allow it to go to certain domain names, and in the zone file all the domains are forwards to the Active directory name server we have running. The issue that I am having is that while on these two VLANS I cannot perform an nslookup properly unless I put in a trailing period. For example,

nslookup will produce
and the IP of the VLAN interface on the Campus Manager box

nslookup will produce
and all the IP's that it resolves to

Not sure whats going on, any help would be appreciated....


Avatar of prashsax

Do you have a "." zone configured on your DNS server.

Or does it have only one zone for your domain only.

Might help -
The appending of "" is a feature if no trailing period is provided - however when I use "nslookup xyz" I get the default domain appended (because it is taken as a machine name) but if I do "nslookup" I don't get the domain appended and I don't think I have a "." zone defined
If it is what i think, it would only occure when nslooking up zones locally hostes, right? Then nslookup is ok without trailling dot?

In the zone config, there is 2 way to set a "A" record. With implicit or explicit domain name.

www IN A IN A

the second one need a dot, the first one doesn't.

Avatar of Amit Bhatnagar
Amit Bhatnagar
Flag of India image

Link to home
This solution is only available to members.
To access this solution, you must be a member of Experts Exchange.
Start Free Trial
On 2nd thoughts I might be tempted to guess that the "Campus Manager" software runs in such a way that certain domain names are resolved by their DNS server depending on what state the machine is in and hence what VLAN they are assigned to.
So "" is defined in their DNS server for 1 VLAN but not for the other VLAN.
Exactly why this has been done can only really be answered by their technical bods but I think it could be a feasible answer as they can then prevent machines from accessing outside sources by forcing DNS lookups to resolve to their own machine which might be a proxy for such sites as "" and therefore they can monitor when a machine is updated and ready to be moved up the chain.
Avatar of concordit


Sorry guys, none of this helped. Basically to simplfy it a bit, I am working on an issue where the DNS server is appending the DNS suffix of the local machine. There is one machine not on an active directory domain and its gets the hostname that the DHCP server is assigning it appened to all nslookups. The machine thats on the active directory domain gets the domain suffixes from the AD domain appended to it, as well as the hostname that the DHCP server is giving it. The DHCP server mind you is on the Campus Manager box, its not the DHCP server on the active directory domain. Unless I put a trailing period I do not get proper returns from nslookup.

My answer concern the campus manager box running linux, not the AD server.  

When you do an nslookup request, specify the IP of the DNS server to force a specific one to provide the info. Do the same test with each server to find out which one cause the problem. The take a look to its own local zone if there is any.
Thats what I did. Local zone is configured with a *. as the A record. Not sure if that has anything to do with it.
OK. First, I got confused as in who is the owner of this question...:)..Anyways, your last comment kinda says the same thing that I think I said about the wild card entry and it may be causing it. Is this wild card entry pointing to some internal webite or something. Also, remove it if possible and see if that takes care of the issue.