Only other suggestion I can think of is to not give DNS server addresses to your AP's. This assumes that you are running seperate subnets for them and control the DHCP server. This would prevent the dns lookup (I'm guessing)

This solution here is to use Primary, Secondary, and Tertiary controller listings for your APs, and then (optionally) configure the controllers for AP Fallback Mode. The DNS lookup is only really used when an AP first comes on the network. At that point you need to log into the controller and give it the needed info. If you have AP Fallback enabled, you're done. If not, you'll need to reboot the AP.

If you have a listing of controller names (not IPs) for each AP, then when it boots it will connect to its primary controller, not what the DNS states.

You'll need to make sure all your controllers are configured for the same Mobility Group for this to work.

I've seen similar issues, where it got a little bit more complex since the controller where the DNS entry resolved to was part of a different mobility group. In this case I had to remove the dns entry, then clear all config, ensure DHCP was set up and reboot the AP to get it back to work.

HTH,

Leo