FSMO Roles

FSMO Roles

In a forest, there are at least five FSMO roles that are assigned to one or more domain controllers. The five FSMO roles are:

•	Schema Master: The schema master domain controller controls all updates and modifications to the schema. To update the schema of a forest, you must have access to the schema master. There can be only one schema master in the whole forest.
•	Domain naming master: The domain naming master domain controller controls the addition or removal of domains in the forest. There can be only one domain naming master in the whole forest.
•	Infrastructure Master: The infrastructure is responsible for updating references from objects in its domain to objects in other domains. At any one time, there can be only one domain controller acting as the infrastructure master in each domain.
•	Relative ID (RID) Master: The RID master is responsible for processing RID pool requests from all domain controllers in a particular domain. At any one time, there can be only one domain controller acting as the RID master in the domain.
•	PDC Emulator: The PDC emulator is a domain controller that advertises itself as the primary domain controller (PDC) to workstations, member servers, and domain controllers that are running earlier versions of Windows. For example, if the domain contains computers that are not running Microsoft Windows XP Professional or Microsoft Windows 2000 client software, or if it contains Microsoft Windows NT backup domain controllers, the PDC emulator master acts as a Windows NT PDC. It is also the Domain Master Browser, and it handles password discrepancies. At any one time, there can be only one domain controller acting as the PDC emulator master in each domain in the forest.

You can transfer FSMO roles by using the Ntdsutil.exe command-line utility or by using an MMC snap-in tool. Depending on the FSMO role that you want to transfer, you can use one of the following three MMC snap-in tools:

Active Directory Schema snap-in
Active Directory Domains and Trusts snap-in
Active Directory Users and Computers snap-in

If a computer no longer exists, the role must be seized. To seize a role, use the Ntdsutil.exe utility.

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Transfer the Schema Master Role

Use the Active Directory Schema Master snap-in to transfer the schema master role. Before you can use this snap-in, you must register the Schmmgmt.dll file.

Register Schmmgmt.dll

1.	Click Start, and then click Run.
2.	Type regsvr32 schmmgmt.dll in the Open box, and then click OK.
3.	Click OK when you receive the message that the operation succeeded.

Transfer the Schema Master Role

1.	Click Start, click Run, type mmc in the Open box, and then click OK.
2.	On the File, menu click Add/Remove Snap-in.
3.	Click Add.
4.	Click Active Directory Schema, click Add, click Close, and then click OK.
5.	In the console tree, right-click Active Directory Schema, and then click Change Domain Controller.
6.	Click Specify Name, type the name of the domain controller that will be the new role holder, and then click OK.
7.	In the console tree, right-click Active Directory Schema, and then click Operations Master.
8.	Click Change.
9.	Click OK to confirm that you want to transfer the role, and then click Close.

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Transfer the Domain Naming Master Role

1.	Click Start, point to Administrative Tools, and then click Active Directory Domains and Trusts.
2.	Right-click Active Directory Domains and Trusts, and then click Connect to Domain Controller. NOTE: You must perform this step if you are not on the domain controller to which you want to transfer the role. You do not have to perform this step if you are already connected to the domain controller whose role you want to transfer.
3.	Do one of the following: • In the Enter the name of another domain controller box, type the name of the domain controller that will be the new role holder, and then click OK. -or- • In the Or, select an available domain controller list, click the domain controller that will be the new role holder, and then click OK.
4.	In the console tree, right-click Active Directory Domains and Trusts, and then click Operations Master.
5.	Click Change.
6.	Click OK to confirm that you want to transfer the role, and then click Close.

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Transfer the RID Master, PDC Emulator, and Infrastructure Master Roles

1.	Click Start, point to Administrative Tools, and then click Active Directory Users and Computers.
2.	Right-click Active Directory Users and Computers, and then click Connect to Domain Controller. NOTE: You must perform this step if you are not on the domain controller to which you want to transfer the role. You do not have to perform this step if you are already connected to the domain controller whose role you want to transfer.
3.	Do one of the following: • In the Enter the name of another domain controller box, type the name of the domain controller that will be the new role holder, and then click OK. -or- • In the Or, select an available domain controller list, click the domain controller that will be the new role holder, and then click OK.
4.	In the console tree, right-click Active Directory Users and Computers, point to All Tasks, and then click Operations Master.
5.	Click the appropriate tab for the role that you want to transfer (RID, PDC, or Infrastructure), and then click Change.
6.	Click OK to confirm that you want to transfer the role, and then click Close.

Thanks and Regards,

Arun Sabale | L2 tech

+919821129229
Zenith Infotech Ltd.

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From: Arun Sabale <Arun.Sabale@zenithinfotech.com>
Sent: Fri, 8/15/2008 2:39am
To: sabale_arun@inbox.com ; Arun Sabale <arun.sabale@zenithinfotech.com>
Subject: FSMO Roles

Windows 2000/2003 Single-Master Model

To prevent conflicting updates in Windows 2000/2003, the Active Directory performs updates to certain objects in a single-master fashion.

In a single-master model, only one DC in the entire directory is allowed to process updates. This is similar to the role given to a primary domain controller (PDC) in earlier versions of Windows (such as Microsoft Windows NT 4.0), in which the PDC is responsible for processing all updates in a given domain.

In a forest, there are five FSMO roles that are assigned to one or more domain controllers. The five FSMO roles are:

Schema Master:

The schema master domain controller controls all updates and modifications to the schema. Once the Schema update is complete, it is replicated from the schema master to all other DCs in the directory. To update the schema of a forest, you must have access to the schema master. There can be only one schema master in the whole forest.

Domain naming master:

The domain naming master domain controller controls the addition or removal of domains in the forest. This DC is the only one that can add or remove a domain from the directory. It can also add or remove cross references to domains in external directories. There can be only one domain naming master in the whole forest.

Infrastructure Master:

When an object in one domain is referenced by another object in another domain, it represents the reference by the GUID, the SID (for references to security principals), and the DN of the object being referenced. The infrastructure FSMO role holder is the DC responsible for updating an object's SID and distinguished name in a cross-domain object reference. At any one time, there can be only one domain controller acting as the infrastructure master in each domain.

Note: The Infrastructure Master (IM) role should be held by a domain controller that is not a Global Catalog server (GC). If the Infrastructure Master runs on a Global Catalog server it will stop updating object information because it does not contain any references to objects that it does not hold. This is because a Global Catalog server holds a partial replica of every object in the forest. As a result, cross-domain object references in that domain will not be updated and a warning to that effect will be logged on that DC's event log. If all the domain controllers in a domain also host the global catalog, all the domain controllers have the current data, and it is not important which domain controller holds the infrastructure master role.

Relative ID (RID) Master:

The RID master is responsible for processing RID pool requests from all domain controllers in a particular domain. When a DC creates a security principal object such as a user or group, it attaches a unique Security ID (SID) to the object. This SID consists of a domain SID (the same for all SIDs created in a domain), and a relative ID (RID) that is unique for each security principal SID created in a domain.  Each DC in a domain is allocated a pool of RIDs that it is allowed to assign to the security principals it creates. When a DC's allocated RID pool falls below a threshold, that DC issues a request for additional RIDs to the domain's RID master. The domain RID master responds to the request by retrieving RIDs from the domain's unallocated RID pool and assigns them to the pool of the requesting DC. At any one time, there can be only one domain controller acting as the RID master in the domain.

PDC Emulator:

The PDC emulator is necessary to synchronize time in an enterprise. Windows 2000/2003 includes the W32Time (Windows Time) time service that is required by the Kerberos authentication protocol. All Windows 2000/2003-based computers within an enterprise use a common time. The purpose of the time service is to ensure that the Windows Time service uses a hierarchical relationship that controls authority and does not permit loops to ensure appropriate common time usage.

The PDC emulator of a domain is authoritative for the domain. The PDC emulator at the root of the forest becomes authoritative for the enterprise, and should be configured to gather the time from an external source. All PDC FSMO role holders follow the hierarchy of domains in the selection of their in-bound time partner.

In a Windows 2000/2003 domain, the PDC emulator role holder retains the following functions:

• Password changes performed by other DCs in the domain are replicated preferentially to the PDC emulator.

• Authentication failures that occur at a given DC in a domain because of an incorrect password are forwarded to the PDC emulator before a bad password failure message is reported to the user.

• Account lockout is processed on the PDC emulator.

• Editing or creation of Group Policy Objects (GPO) is always done from the GPO copy found in the PDC Emulator's SYSVOL share, unless configured not to do so by the administrator.

• The PDC emulator performs all of the functionality that a Microsoft Windows NT 4.0 Server-based PDC or earlier PDC performs for Windows NT 4.0-based or earlier clients.

This part of the PDC emulator role becomes unnecessary when all workstations, member servers, and domain controllers that are running Windows NT 4.0 or earlier are all upgraded to Windows 2000/2003. The PDC emulator still performs the other functions as described in a Windows 2000/2003 environment.

At any one time, there can be only one domain controller acting as the PDC emulator master in each domain in the forest.