Use netdom to find where the current FSMO roles are assigned in Active Directory:

netdom query fsmo

This will return something like:

Schema master                DC01.local
Domain naming master         DC02.local
PDC                          DC01.local
RID pool manager             DC02.local
Infrastructure master        DC01.local
The command completed successfully.

The 'netdom query' command can also return other useful information. Valid types include:

Server, Workstation, DC, OU and Trust