Integration GTM and actual DNS architecture

It's supported. You just delegate name resolution of the A record you want to the GTM.

 

 

In your DNS server you create a subdomain of mydomain.com, for example, gtm.mydomain.com, and delegate it to your GTM.

 

Then, for each A record you want to be treated by the GTM, you create an alias (CNAME record), like:

 

 

access.mydomain.com -> access.gtm.mydomain.com

 

 

You can read about that in "BIG-IP® Global Traffic Manager™:Implementations", chapter "Delegating DNS Traffic to Wide IPs", available in F5 Website.