It is complicated to keep the subsystem JGroups in sync if the tcp-stack is used in domain mode.
All new servers that join/leave a clustered server group (configuration) must be added or removed by hand for the jgroup configuration.

The domain server will receive the information if a host-controller enrol and register server to a clustered server-group.
So the configuration of the initial_hosts can be done automatically to avoid old entries which cause unnecessary checks and ensure that all active servers are known.