Conditional forwarder issue

abrarali · 2024-01-30T14:41:11.000Z

I have set up a conditional forwarder to resolve a host name internally when on the office network. However, sometimes the ping resolves to an external IP rather than an internal IP, and a quick DNS cache clear or restart resolves the issue. The same forwarder is working from other DCs. However, it is causing significant issues as the application is not working.

This has been going on for a month, and in the meantime, I have tried capturing packets but was unable to find any conclusive leads. There are no DNS errors in the event viewer, and I have also run the DNS test “dcdiag /e /i /c,” finding no errors.

Any help would be greatly appreciated.

@philipvandeneynde7308

matt7863 · 2024-01-30T19:46:19.000Z

Is this windows dns server?

Test using nslookup to check it always resolves correctly. You may find that sometimes it times out - this would cause the server to try its other dns servers (forwader/root hint).

From this thread DNS Conditional Forwarder to Azure stops working ErkinD39 advises two useful options for the conditional forwarder. Set using PowerShell you can change the timeout -ForwarderTimeout and also set it to not use recursion if it fails : -UseRecursion $false

abrarali · 2024-02-02T07:31:08.000Z

Thanks for you suggestion Matt. I have changed the timeout settings and also set the -UseRecursion $false. It has been more than 24 hours and we haven’t had any complaints so far.