Active Directory Partitions

Each Domain Controller has a copy of the Active Directory database store in a file called NTDS.DIT. The data in this file is divided into partitions. The partition type determines how it will be replicated throughout the forest. For example, the domain partition is only replicated to Domain Controllers in that domain, while the Global Catalog partition is replicated to all Domain Controllers in the forest.

Domain Partition

This partition is replicated only to Domain Controllers in that domain. Active Directory Users and Computers obtains it data from this partition. All Domain Controllers in that domain replicate changes to each other regardless of whether the Domain Controller is a global catalog server.

Global Catalog Partition

This partition is also referred to as Partial Attribute Set (PAS) in some documents. The partition contains a partial replica of all objects in the domain. It is replicated to all Global Catalog Servers in the forest.

The Global Catalog Partition is created automatically by software on the Domain Controller. This software copies some of the attributes for each object in the Global Catalog Partition. This information is replicated to other Domain Controllers inside and outside the domain. This is how, given enough time, all Global Catalog servers will have a partial replicate of all objects in the domain.

Schema Partition

The schema partitions define what can be stored in the Active Directory database. It essentially defines the layout of the database. The schema partition is replicated to all Domain Controllers in the forest and defines the Active Directory database for all Domain Controllers in the domain.

Configuration Partition

This partition contains configuration information for the whole forest. For example, it contains information about sites in the forest and partition defined in the Active Directory database. This partition is replicated to all Domain Controllers in the forest.

Application Partition

The application partition is created by Applications to store their data. It is different from any other partition in that the application can choose which Domain Controller or Controllers to store the data on. The advantage for the application storing the data this way is that the application has access to the same replicate and fault tolerance used by the Domain Controllers. An example of an Application is DNS Integrated Active Directory Zones. When this zone type is used, the data is stored in an application partition.