DNS Persistence in GTM

The GTM's have an option for persistence in the load balancing of the pools. So when a LDNS requests an IP address, it gets the same IP each time for as long as the persistence TTL is set to last. This is a drop down item from the GUI.

As far as the Akamai cloud persistence, the GTM will reply to LDNS requests. So if a user session coming from the Akamai cloud uses the same LDNS, then they will get the persistence to the DC specified through the GTM's persistence as mentioned above.

If every edge server will be doing its own LDNS request and a user session will switch edge servers during a session, you could attempt a topology based solution if you know that the edge servers for a session will come from a specific IP range. If the IPs of LDNS requests are going to be random or too many to enumerate, you'll need to coordinate with Akamai.