The Relationship Of Site And Domain Structures

By Author: Mike Jones
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As an administrator, you must create a site structure to reflect your company's organization. See MCTS exam, "Planning the Active Directory Infrastructure Design," to learn the basics of site design. See Chapter 5, "Configuring Sites and Managing Replication," for details about configuring sites.
Domain Controllers A domain controller is a computer running Windows Server 2003 that stores a replica of the domain directory (local domain database). Because a domain can contain one or more domain controllers, each domain controller in a domain has a complete replica of the domain's portion of the directory. A domain controller can service only one domain. A domain controller also authenticates user logon attempts and maintains the security policy for a domain.
The following list describes the functions of domain controllers:
Each domain controller stores a complete copy of all Active Directory information for that domain, manages changes to that information, and replicates those
changes to other domain controllers in the same domain.
Domain controllers in a domain ...
... automatically replicate directory information for all objects in the domain to each other. When you perform an action that causes an update to Active Directory, you are actually making the change at one of the domain controllers. That domain controller then replicates the change to all other domain controllers within the domain. You can control TS windows 7 configuration replication of traffic between domain controllers in the network by specifying how often replication occurs and the amount of data that each domain controller replicates at one time.
Domain controllers immediately replicate certain important updates, such as the disabling of a user account.
Active Directory uses multimaster replication, in which no one domain controller is the master domain controller. Instead, all domain controllers within a domain are peers, and each domain controller contains a copy of the directory database that can be written to. Domain controllers can hold different information for short periods of time until all domain controllers have synchronized changes to Active Directory.
Although Active Directory supports multimaster replication, some changes are impractical to perform in multimaster fashion. One or more domain controllers
can be assigned to perform single-master replication (operations not permitted to occur at different places in a network at the same time). Operations master roles are special roles assigned to one or more domain controllers in a domain to perform single-master replication.
Domain controllers detect collisions, which can occur when an attribute is modified on a domain controller before a change to the same attribute on another
domain controller is completely propagated. Collisions are detected by comparing each attribute's property version number, a number specific to an attribute that is initialized upon creation of the attribute. Active Directory resolves the collision by replicating the changed attribute with the higher
free Microsoft certification exam papers property version number.