DNS responding only to nslookup in Windows 7

Question

I have an interesting DNS issue in AD (2008R2) which I can't find a way to debug. Mainly if from commandline I try

ping <machinename>

then I get the reply that the hostr isn't found. But when I do

nslookup <machinename>

I get the correct response from my DNS with proper AAAA and A records. Anyone has an idea what could cause this?

The client machines run Windows 7 Enterprise.

Answer 1

Make sure HOSTS and LMHOSTS doesn't have anything funny in it. nslookup works by talking directly to the DNS server, whereas the name resolution ping uses is done by the operating system. This means that your HOSTS file could be screwed, or there's corruption on Winsock etc etc.

Since we're playing with IPv4 and IPv6, what happens when you ping host -4 and ping host -6?

You may also want to turn off WINS/NetBIOS

Answer 2

Previous comments are right. I would simply add that there MAY be a sequence for name resolution. At least, this exists under Linux as a file named /etc/nsswitch. By default, a local HOST file will resolve names BEFORE invoking a name server. As for the actual IP addresses of the name servers, those are setup in Control Panel -> Network

Usually, the HOSTS file is located under C:\WINDOWS\SYSTEM32\DRIVERS\ETC

This file can be edited using notepad. I use this file all the time on the various virtual Windows servers I have.

Answer 3

I just had exactly the same issue. For me the issue was caused by having multiple DNS servers defined. My IPv4 settings were set to DHCP with the primary DNS set to my router and the secondary DNS set to a Google DNS server. Although the order doesn't matter.
When I switch to use the DNS server provided via DHCP the issue is resolved. Adding the DNS servers back brings back the issue.

I really don't understand the root cause of this. But maybe it's the same issue for you.

Answer 4

I've run into Vista systems caching null dns entries if a dns server was not available. Running "ipconfig /flushdns" cleared them out. Depending on what the root cause is this might only be a bandaid fix but have a look at disabling the caching of negative dns results. There are decent instructions here

Answer 5

Out of the box Windows 7 disables Ping response in Windows Firewall. You'll need to switch it on in all of the client machines. Not sure if this can be done via group policy. Here is how to do it on Vista, I'm guessing 7 is the same.