Normally, when GTM answers a DNS query for a property name, it chooses a data center and then returns IP addresses for every live server in the data center.
If you need to be able to perform a single DNS query that returns every server in every data center for a property, regardless of liveness, you can use a round-robin prefix. A round-robin prefix is a string that when configured automatically creates a shadow property for each normal property. The shadow property's name is the round-robin prefix followed by an underscore and then the normal property name.
For example, if a property named roundrobin is in the domain test.akadns.net and the round-robin prefix is showall, you can issue a DNS query for showall_roundrobin.test.akadns.net . This query returns all the IP addresses in all data centers for the property.
The handout limit applies to the maximum number of IP addresses that can be returned.
To configure a round-robin prefix for a domain, submit a ticket to Akamai Support.