domain tree. Moving FSMO roles between domain controllers By default AD assigns all operations master roles to the first DC created in a forest. To provide fault tolerance, there should be multiple domain controllers available within each domain of the Forest. If new domains are created in the forest, the first DC in a new domain holds all of the domain-wide FSMO roles. This is not a satisfactory position if the domain has a large number of domain controllers. Microsoft recommends the careful division of FSMO roles, with standby DCs ready to take over each role. The PDC emulator and the RID master should be on the same DC, if possible. The Schema Master and Domain Naming Master should also be on the same DC. When a FSMO role is transferred to a different DC, the original FSMO holder and the new FSMO holder communicate to ensure no data is lost during the transfer. If the original FSMO holder experienced an unrecoverable failure, another DC can be made to "seize" the lost roles; however, there is a risk of data loss because of the lack of communications. Seizing roles from a domain controller instead of transferring it prevents that domain controller from hosting that FSMO role again, except for the PDC Emulator and Infrastructure Master Operation roles. Corruption can occur within Active Directory. FSMO roles can be easily moved between DCs using the AD snap-ins to the MMC or using ntdsutil, which is a command line-based tool. FSMO Roles and Global Catalog Certain FSMO roles depend on the DC being a Global Catalog (GC) server as well. When a Forest is initially created, the first Domain Controller is a Global Catalog server by default. The Global Catalog provides several functions. The GC stores object data information, manages queries of these data objects and their attributes as well as provides data to allow network logon. Often all domain controllers are also global catalog servers. If this is not the case, the Infrastructure Master role must not be housed on a domain controller which also houses a copy of the global catalog in a multi-domain forest, as the combination of these two roles on the same host will cause unexpected (and potentially damaging) behaviour in a multi-domain environment. However, The Domain Naming Master role should be housed on a DC which is also a GC. References External links Active Directory Microsoft server