Sporadic external DNS lookup failure

[Proteus]

I have recently shifted from Windows Server 2003 to Windows Server 2008 due to which I had to update the DNS server also. But after transition to the new system, all the external DNS lookups fail frequently. The only way to get the system back to working state is to restart the DNS server services. I tried many things but was not able to solve the Sporadic external DNS lookup failure and hence need your help. Any help regarding the topic are more than welcome.

[Snake08]

Are there any forwarders configured on the server? By the description of the problem which you have given, I think it is due to wrong configurations of the forwarders. Mostly forwarders once configured, are not be looked up again. But as you are facing external DNS lookup failures, I will suggest that you check the configuration of the forwarders and make changes if necessary. You can also try and disable the forwarders to check if the domain is working properly or not.

[Zachary]

According to me the problem is with Extended mechanism for DNS or EDNS. Both the operating systems have an EDNS. As you have migrated from 2003 to 2008 it is possible that EDNS was disabled in 2003 and now after migrating on 2008 it is creating some problems. Hence you will have to turn off the EDNS support in 2008. To disable the EDNS support use the following command

dnscmd /config /enableednsprobes 0

Hope it helps.

[Shen]

If there is any firewall installed, then it is possible that the firewall is blocking the UDP traffic on the server due to which the DNS lookup is failing. Therefore if there is firewall installed on the server, then configure it to handle files more than 512 bytes and save the configuration. After saving the configuration, check if the problem still persists or not.

[Proteus]

As suggested, I changed the firewall settings on the server but it did not change anything. Still the server is giving same error while external DNS lookup. I also changed the settings for the EDNS and disabled it but still no progress. So are there any alternate solutions for the problem? Please help.

[CPU09]

Don't know if you've already checked this or not but if you have forwarders configured is your external dns provider responding to ping by IP address? This could be the result of a third party outage!

[Candace]

I would suggest that you dig into the sniffing results and check if the reports contain any failed requests. Check for the outgoing requests and see if there are any inbound responses to it or not. For that you can match up the packets using the UDP source port for the outbound request and destination port for the inbound response.

[addie]

The issue which you are facing is a known issue with Microsoft. The problem is caused because of the 2008 server changing the TTL for the glue records transferred with NS records. There is one workaround for solving the issue. Change the parameters of the following key :-

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\DNS\Parameters MaxCacheTtl

to 0x2A300 (172800 in decimal) also you can clear the cache periodically.