FSMO placement and optimization on Active Directory domain controllers
Certain domain and enterprise-wide operations that are not well suited to multi-master updates must be performed on a single domain controller in the domain or in the forest. The purpose of having a single-master owner is to define a well-known target for critical operations and to prevent the introduction of conflicts or latency that could be created by multi-master updates. Having a single-operation master means that the relevant FSMO role owner must be online, discoverable, and available on the network by computers needing to perform FSMO dependent operations.