[Samba] identifying servers

[Norbert Wegener]

I want to use freeradius and Active directory for authentication in a 
larger Active Directory forest and therefore freeradius must know the 
relevant domain servers.
As this forest is living with servers beeing added and removed, I want 
to identify the global catalog servers in that forest automatically.
How could this be achieved using samba tools?
Thanks
Norbert Wegener