1

Having a problem with a Windows Server 2003.

It's the DNS server for the local LAN it forwards requests to "8.8.4.4" and has been working fine for years. Now today all external DNS requests are timing out.

If run nslookup www.google.co.uk from the server I get

"DNS Request timed out"

if inside of nslookup I change the DNS server to 8.8.4.4 and run the same request I also get "request timed out"

I can successfully connect to 8.8.4.4 on port 53 via telnet so there is connectivity.#

Any ideas on what to check?

Thanks.

3

It looks like you can not reach 8.8.4.4 on 53/UDP.

Have you tried using another public DNS, like OpenDNS ( 208.67.222.222 / 208.67.220.220 ) to see if it is specific to Google DNS ?

If the test with OpenDNS fails, you might want to check if your firewall (Windows or routing infrastructure) / ISP is not dropping the 53/UDP packets for some reason.

You did not specify where you are testing, if it happens on a client machine it might be the DNS server on Windows Server that is refusing connections (firewall, listening interface), if it happens on the Windows Server machine it is quite sure that it is the firewall or an external problem.

  • Your right it was the router I rebooted its now fine. Thanks. – 0x7c0 Jan 2 '13 at 15:06
1

with telnet to port 53 you just test the tcp connectivity to the server. your windows 2003 server uses udp for name resolution. tcp is just used for domain transfers and when the response data size exceeds 512 bytes. have a look at your firewall. i think udp port 53 ist closed.

  • Plus one for the info. It turned out to be the router, I rebooted it and now its working again. Damn DrayTek! – 0x7c0 Jan 2 '13 at 15:06

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