Below article point us to root caused with AP discovery. DNS was added 2 days after HQ when they made their WIFI controller alive 4/5 days ago. Hence lost of comms to AP from 2.17 (controller).
We planning to move to out own domain and use different domain controller.
DNS based controller discovery -
https://www.flomain.de/2014/07/how-to-controller-discovery/
This is a very handy method, when you can not change the VLAN, the AP will be placed into or you want to be very flexible where to connect your AP’s. The AP will get an IP address from a DHCP server and will start L2 controller discovery. As this will fail, the AP will try to get the controller IP via DNS.
When working with MSM controllers, the AP will try to resolve those names:
- cnsrv1.your-domain.com
- cnsrv2.your-domain.com
- cnsrv3.your-domain.com
- cnsrv4.your-domain.com
- cnsrv5.your-domain.com
It is not necessary, to resolve all the names. Just on for every controller and you are fine.
When you have a unified controller, the AP will try to resolve a different name, which is:
- HPN.your-domain.com
If you have more than one controller, you should resolve all IP addresses from that name. Doing it that way, with a round robbing algorithm at the DNS server, will lead to a good sharing of AP’s between those controllers.
Keep in mind, that all AP’s will come with a MSM image, even when you have a unified controller and even after a hard reset, the AP will boot up with a MSM boot code. This mean, you should always put both name formats into your DNS system.
C:\MSM>nslookup cnsrv1
Server: har-ad8-01.stc.ricplc.com
Address: 172.31.4.50
Name: cnsrv1.stc.ricplc.com
Address: 172.30.69.48
C:\MSM>nslookup cnsrv2
Server: har-ad8-01.stc.ricplc.com
Address: 172.31.4.50
*** har-ad8-01.stc.ricplc.com can't find cnsrv2: Non-existent domain
C:\MSM>nslookup hpn
Server: har-ad8-01.stc.ricplc.com
Address: 172.31.4.50
Name: hpn.stc.ricplc.com
Address: 172.30.69.48