Windows 2012 host can ping but no DNS lookup

Windows 2012 host can ping but no DNS lookup

Windows 2012 host can ping but no DNS lookup

Had an interesting issues today. Windows 2012 fully patched on ML620 Blade with a trunk port connected to PowerConnect with QLogic. The server was able to ping to AD DNS (windows 2008 R2), and other servers in the network, telnet 53 over TCP to our DNS server (well, I have not gone through sniffing UDP 53 port). In other words, the connection between this server and DNS server seem to have no issues. But, when we tried DNS lookup via nslookup or ping etc, we got “DNS request timed out”. It was not able to query the DNS at all.

Below is what you need to investigate:

Windows 2012 host can ping but no DNS lookup

Here is what to blame:

  • Large Send Offload
  • TCP Checksum offload

on the NIC driver. When either of these were enabled, the server could not query the DNS. I have not had a time to dive into “why”. 

So, it might be good to play with these if you are having similar issues

 

Large Send Offload V2 Checksum Offload

Not: The behavior was still the same when we installed the latest drivers from the vendor.

Good luck.

Bulent Tolu

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