Due to the distributed nature of Active Directory, it is necessary to segregate data into partitions. If data partitioning were not used, every domain controller would have to replicate all the data within a forest. Often it is advantageous to group data based on geographical or political requirements. Think of a domain as a big data partition, which is also referred to as a naming context (NC). Only domain controllers that are authoritative for a domain need to replicate the information within it. On the other hand, there is some Active Directory data that must be replicated to all domain controllers. There are three predefined naming contexts within Active Directory:
A Domain Naming Context for each domain
The Configuration Naming Context for the forest
The Schema Naming Context for the forest
Each of these naming contexts represents a different aspect of Active Directory data. The Configuration NC holds data pertaining to the configuration of the forest, for example, the objects representing naming contexts, LDAP policies, sites, subnets, and so on. The Schema NC contains the set of object class and attribute definitions for the types of data that can be stored in Active Directory. Each domain in a forest also has a Domain NC, which contains data specific to the domain, for example, users, groups, computers, etc.
In Windows Server 2003 Active Directory, Microsoft extended the naming context concept by allowing user-defined partitions called application partitions. Application partitions can contain any type of object except security principals, such as user objects. The major benefit of application partitions is that administrators can define which domain controllers replicate the data contained within them. Application partitions are not restricted by domain boundaries, as is the case with Domain NCs.
You can retrieve a list of the naming contexts and application partitions a specific domain controller maintains by querying its Root DSE entry. You can view the Root DSE by opening the LDP utility, which is available from the Windows Support Tools. Select Connection Connect from the menu, enter the name of a domain controller, and click OK. The following attributes pertain to naming contexts and application partitions:
List of DNs of all the naming contexts and application partitions maintained by the DC.
DN of the Domain NC the DC is authoritative for.
DN of the Configuration NC.
DN of the Schema NC.
DN of the Domain NC for the forest root domain.
In this chapter, we will review each of the three predefined naming contexts and describe the data contained within each, and then cover application partitions and example uses.