There is a very good chance that you will encounter at least one question pertaining to the Flexible Single Master Operation (FSMO) roles on one of your MCSE or MCSA exams. What it comes down to is that you need to know what the different roles are used for, whether they are forest wide or domain wide and how to transfer a role to another server. For the Active Directory design exam, you also need to get into the specifics about where you should place the different servers functioning in these roles.

Let’s start by taking a look at what the FSMO roles are. With the multi-master replication model, most changes made can be made on any domain controller and replicated throughout the domain. These changes include day-to-day tasks such as adding user accounts, changing account properties, or updating policy settings.

However, there are some operations that can only be performed in one server. For these types of operations, there are specific domain controllers that are designated as being Operation Masters and they become responsible for receiving certain updates. The domain controllers that are assigned these roles become “role owners” for the specific operations. The five different Operation Master roles include:

• Schema Master
• Domain Naming Master
• Relative ID Master
• Primary Domain Controller Emulator Master
• Infrastructure Master

Of the five operation master roles, two of the roles are forest-wide and the remaining three are domain-wide. For each forest-wide role, there is only one domain controller designated the role owner for that specific operation throughout the entire forest. The two operation master roles that are forest-wide are the Schema Master and the Domain Naming Master.