DOMAIN CONTROLLER

Domain Controllers

Any server on which you have installed Active Directory is a domain controller. These servers authenticate all users logging on to the domain in which they are located, and they also serve as centers from which you can administer Active Directory in Windows Server 2008. A domain controller stores a complete copy of all objects contained within the domain, plus the schema and configuration information relevant to the forest in which the domain is located. Unlike Windows NT, there are no primary or backup domain controllers. Similar to Windows 2000 and Windows Server 2003, all domain controllers hold a master, editable copy of the Active Directory database.

Every domain must have at least one DC. A domain may have more than one DC; having more than one DC provides the following benefits:

• Fault tolerance: If one domain controller goes down, another one is available to authenticate logon requests and locate resources through the directory.
• Load balancing: All domain controllers within a site participate equally in domain activities, thus spreading out the load over several servers. This configuration optimizes the speed at which requests are serviced.