Proper placement of FSMO Roles boils down to three simple rules:
- Rule One: In your forest root domain, keep your Schema Master and Domain Naming Master on the same domain controller to simplify administration of these roles, and make sure this domain controller contains a copy of the Global Catalog. This is not a hard-and-fast rule as you can move these roles to different domain controllers if you prefer, but there’s no real gain in doing so and it only complicates FSMO role management to do so. If for reasons of security policy however your company decides that the Schema Master role must be fully segregated from all other roles, then go ahead and move the Domain Naming Master to a different domain controller that hosts the Global Catalog. Note though that if you’ve raised your forest functional level to Windows Server 2003, your Domain Naming Master role can be on a domain controller that doesn’t have the Global Catalog, but in this case be sure at least to make sure this domain controller is a direct replication partner with the Schema Master machine.
- Rule Two: In each domain, place the PDC Emulator and RID Master roles on the same domain controller and make sure the hardware for this machine can handle the load of these roles and any other duties it has to perform. This domain controller doesn’t have to have the Global Catalog on it, and in general it’s best to move these two roles to a machine that doesn’t host the Global Catalog because this will help balance the load (the Global Catalog is usually heavily used).
- Rule Three: In each domain, make sure that the Infrastructure Master role is not held by a domain controller that also hosts the Global Catalog, but do make sure that the Infrastructure Master is a direct replication partner of a domain controller hosting the Global Catalog that resides in the same site as the Infrastructure Master. Note however that this rule does have some exceptions, namely that the Infrastructure Master role can be held by a domain controller hosting the Global Catalog in two circumstances: when there is only one domain in your forest or when every single domain controller in the domain also hosts the Global Catalog.
To summarize these three rules then and make them easy to remember:
- Forest root domain – Schema Master and Domain Naming Master on the same machine, which should also host the Global Catalog.
- Every domain – PDC Emulator and RID Master on the same machine, which should have beefy hardware to handle the load.
- Every domain – Never place the Infrastructure Master on a machine that hosts the Global Catalog, unless your forest has only one domain or unless every domain controller in your forest hosts the Global Catalog.