Overview#Flexible Single Master Operation (FSMO) is a specialized Domain Controller (DC) set of tasks, used where standard data transfer and update methods are inadequate.
Microsoft Active Directory normally relies on multiple peer Domain Controllers, each with a copy of the AD database, being synchronized by multi-master replication. The tasks which are not suited to multi-master replication and are viable only with a single-master database are the Flexible Single Master Operations.
Flexible Single Master Operation extends the single-master model found in earlier versions of Windows to include multiple roles, and the ability to transfer roles to any domain controller (DC) in the enterprise. Because an Active Directory role is not bound to a single DC, it is referred to as a Flexible Single Master Operation (FSMO) role. Currently in Windows there are five FSMO roles:
- AD Forest.
- AD DOMAIN