FSMO ( Flexible Single-Master Operation )

TYPE: 1Flexible Single-Master Operation (FSMO) roles, manage an aspect of the domain or forest, to prevent conflicts

1. Domain Naming Master, If you want to add a domain to a forest, the domains name must be verifiably unique. The forests Domain Naming Master FSMOs authorize the domain name operation.

2. Infrastructure Master, When a user and group are in different domains, a lag can exist between changes to the user (e.g., a name change) and the users display in the group. The Infrastructure Master of the groups domain fixes the group-to-user reference to reflect the change. The Infrastructure Master performs its fixes locally and relies on replication to bring all other replicas of the domain up to date.

3. PDC Emulator, For backward compatibility, one DC in each Win2K domain must emulate a PDC for the benefit of Windows NT 4.0 and NT 3.5 DCs and clients.

4.RID Master, The RID Master must be available for you to use the Microsoft Windows 2000 Resource Kits Move tree utility to move objects between domains.

5. Schema Master, At the heart of Active Directory (AD) is the schema, which is like a blueprint of all objects and containers. Because the schema must be the same throughout the forest, only one machine can authorize schema modifications.TYPE: 2FSMO ROLES MEANS FLIXIBLE SINGAL MASTER OPREATION. MEANS ALL THESE MASTER ROLE CAN BE SHIFTT OR CHANGE.THER ARE FIVE ROLES.WHEN U INSTALLED THE FIRST DOMAIN IN THE FOREST THEY ALL FIVE ROLES ARE INSTALLED ON THAT, BUT DUE TO EVERY ROLES HAS ITS OWN RESPONSIBLEITIES SO THAT THER IS A RISK TO SLOWE DOWN THE SERVER IN ALL THAT FIVE ROLES FIRST TWO ROLES ARE CALLED FOREST WIDE ROLES THAT ARE 1. SCHEMA MASTER ROLE. 2. IS DOMAIN NAMING MASTER ROLE. THESE ROLES SHOULD BE ON THE FIRST DOMAIN OF THE FOREST.1. SCHEMA MASTER ROLE: THIS ROLES HAS ALL THE SCHEMA INFORMATION OF THE FOREST.2. DOMAIN NAMING MASTER: THIS ROLE HAS THE INFORMATION OF ALL THE DOMAIN IN THE FOREST. SO WHEN U INSTALL THE NEW DOMAIN IN THE FOREST SO THAT IT FIRST CONTECT TO THE DOMAIN NAMING MASTER TO AVOID THE CONFILECTS.OTHER THREE ROLES KNOWN AS DOMAIN WIDE ROLES. 3. PDC EMULATOR. 4. RID MASTER. 5. INFRASTRUTURE MASTER.THESE ROLES ARE FIND IN EVERY DOMAIN IN THE FOREST. 3. PDC EMULATOR ROLE: THIS IS RESPONSIBLE FOR THE AUTHENTICATION OF THE NT 4 CLIENTS. 4. RID MASTER: THIS ROLES GIVE THE RID'S TO THE DOMAINS AND RESPOSIBLE TIME SYNCORNISATION WITH THE DOMAIN IN THE FOREST.5. INFRSTRUTURE MASTER: THIS ROLE REPLICATE ALL THE INFORMATIONTO GLOBAL CATLOG TO MANAGE OBJECT FOR INTER DOMAIN INTEROPRABILITY.

TYPE: 3For certain types of changes, Windows 2000/2003 incorporates methods to prevent conflicting Active Directory updates from occurring.

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:

1.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.

2.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.

3.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.

4.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.

5.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.

TYPE: 3FSMO - Stands for Flexible Single Master Operation.

The purpose of this FSMO is to avoid the conflicts through out the forest . Conflicts will be like domain names,Objects, Fields ..etc.

Usually FSMO broadly divided into 5 Roles.

1. Schema Master Role2. Domain Naming Master Role

3. RID - Relative Identifier.4. PDC Emulator.5. Infrastructure.

You can easily differentiate the first one and two will be Forest wide and the rest 3,4 and 5 will be domain wide.

1. Schma Master :- Operations that involve expanding user properties e.g. Exchange 2003 / forestprep which adds mailbox properties to users. Rather like the Domain naming master, changing the schema is a rare event. However if you have a team of Schema Administrators all experimenting with object properties, you would not want there to be a mistake which crippled your forest. So its a case of Microsoft know best, the Schema Master should be a Single Master Operation and thus a FSMO role.

2.Domain Naming Master - Ensures that each child domain has a unique name. How often do child domains get added to the forest? Not very often I suggest, so the fact that this is a FSMO does not impact on normal domain activity. My point is it's worth the price to confine joining and leaving the domain operations to one machine, and save the tiny risk of getting duplicate names or orphaned domains.

3.PDC Emulator - Most famous for backwards compatibility with NT 4.0 BDC's. However, there are two other FSMO roles which operate even in Windows 2003 Native Domains, synchronizing the W32Time service and creating group policies. I admit that it is confusing that these two jobs have little to do with PDCs and BDCs.

4.RID Master - Each object must have a globally unique number (GUID). The RID master makes sure each domain controller issues unique numbers when you create objects such as users or computers. For example DC one is given RIDs 1-4999 and DC two is given RIDs 5000 - 9999.

5.Infrastructure Master - Responsible for checking objects in other other domains. Universal group membership is the most important example. To me, it seems as though the operating system is paranoid that, a) You are a member of a Universal Group in another domain and b) that group has been assigned Deny permissions. So if the Infrastructure master could not check your Universal Groups there could be a security breach.