Forum Discussion
Hi James,
Running into kinda the same issue atm; Windows DNS server(s) (still need to confirm the OS version and release) quering BIGIP DNS (version 12.1.3.6 Build 0.0.3 Point Release 6).
Same concept as you described: Corp DNS also has CNAME Records that will do global resolution, example would be CNAME funkytown.ilb.blank.com Alias funkytown.blank.com. Corp DNS would send that request to the Internal F5 DNS server that responds back with an A record with IP address. Corp DNS is the SOA for blank.com and the F5 DNS is the SOA for ilb.blank.com
The clients receive an incomplete answer to their query: the fqdn is there but no IP address. When this happens no query is sent to the BIGIP (confirmed in BIGIP logs).
Nothing of a clue as to why this happens let alone a fix.
PS> there used to be an issue in Win. 2008 R2 - https://support.microsoft.com/en-us/help/3022780/dns-server-does-not-respond-with-ip-address-to-a-cname-query-for-a-del
Piarea,
After many packet captures and many hours trying to figure out this issue, we had tickets open with Microsoft and F5 support and no one was able to resolve our issue. Finally we were able to resolve this issue, I decided to take a drastic approach to fix this. For some reason Microsoft DNS and it not getting a valid SOA record cause the lb.blank.com zone in caching will never respond with a SOA, was intermittently thinking he was the SOA of this zone and since he had no local record he would respond incorrectly.
The FIX: create a DNS express Profile, and put your Zone in it, this will now respond back to CORP DNS with a Valid SOA record. This was the FIX for our issue.
Also if you have a external Big IP DNS that you forward DNS requests to from your internal BigIP DNS you will need to change that the caching forwarder does not work correctly we had to remove this and just create another NS delegation on CORP DNS to send direct to our external BigIP DNS.
thanks