If a user is on a site and using Z-APP, the GRE tunnels on the site are connected to a Datacentree that is listed as “Not in gateway”, is there some intelligence that recognises this or does it just connect to the DC’s as per the geo located $gateway variable.
Z App itself will connect to the gateway definition in the App Profile PAC. This could mean you setting to a specific data center so Z App sends traffic there. But, Z App can also connect through an existing GRE. I would imagine that the traffic would go through that location and still destined to the $Gateway returned after passing through.