FSMO Placement Guidance Summary:

• Make sure the PDC is highly available and connected.
• Place the PDC on your best hardware in a reliable hub site that contains replica domain controllers in the same Active Directory site and domain.
• Place the Forest FSMOs on the forest root PDC (schema master & domain naming master).
• Place the RID master on the domain PDC in the same domain.
• If you have a single domain environment, all DCs are GCs, OR you have enabled the recycle bin (see MSDN note below), place the infrastructure master on the PDC (which likely contains the other FSMO roles as well).
• Don’t move FSMOs around regularly. The PDC is targeted for a number of operations and network connections. It is best to not force clients to rediscover the PDC on a regular basis.

This means, in a single domain environment, it makes sense to place all the FSMOs on a single DC. Pick one that is highly available and well-connected. You may decide that selecting a virtual DC is the way to go since it can usually be moved to different hosts for DR/COOP reasons. Note that if you do go virtual for this DC, consider disabling VM host time synchronization.Though, there may be valid reasons for not doing so.

In a multiple domain environment, place the Forest FSMOs on the forest root PDC (schema master & domain naming master) and select one DC per domain on which to place all of the FSMOs – the PDC is a good choice assuming they are all GCs or the AD Recycle Bin is enabled.

MSDN NOTE:

When the Recycle Bin optional feature is enabled, every DC is responsible for updating its cross-domain object references in the event that the referenced object is moved, renamed, or deleted. In this case, there are no tasks associated with the Infrastructure FSMO role, and it is not important which domain controller owns the Infrastructure Master role.

From MSDN: “6.1.5.5 Infrastructure FSMO Role“

FSMO Role Information:
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