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I have a problem with a ubuntu-10.4 VM. When I try to resolve a hostname (using for example nslookup or firefox), my DNS server receive an UDP packet with a DNS query (I saw it with tcpdump), but it drop the request. I tried with a Windows DNS server and a Red Hat DNS server: they receive the query but give no answer. I'm shure that at the end of the installation the name resolution worked !

I have another linux VM: the same query get a response. Comparing requests with tcpdump and wireshark I found no differences between them.

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Post the IPTables rules – James Lawrie Dec 3 '10 at 13:34
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Feels like a routing issue to me – Chopper3 Dec 3 '10 at 13:43
Ther isn't any firewall. tcpdump show me that dns server receive a query and doesn't send any response: I run tcpdump on the server and for a 'normal' client I see an UDP packet containing a response. It seems to me a problem with a corrupted request, but wireshark doesn't show errors in the packet containing the request. – user38412 Dec 3 '10 at 13:49

1 Answer

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Try:

  • Check that the DNS server is configured to listen on that IP network
  • Turn on DNS query logging to see if the DNS server is getting the request
  • Check the DNS server listening on UDP (OK, this is a long shot)

I agree with James Lawrie that you double check your firewall rules

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