The active directory database is stored in a single NTDS.dit file which is logically separated into the following partitions:
- Schema Partition
- Configuration Partition
- Domain Partition
- Application Partition
There is only one schema partition per forest and it is stored in all DCs of the forest. It contains the definition of objects and rules for their manipulation and creation in an active directory. It is replicated to all DCs of the forest.
Just like schema partition, there is just one master configuration partition per forest and a second one on all DCs in a forest. It contains the forest-wide active directory topology including DCs and sites and services. It is replicated to all DCs in a forest.
Many domain partitions exist per forest and they are stored on all DCs in a domain. They contain information about users, groups, computers and OUs. It is replicated to all DCs in a given domain.
This partition stores information about applications in an AD. Suppose AD integrated DNS zones information is stored in this partition.