*Schema NC, *Configuration NC, * Domain NC

Schema NC This NC is replicated to every other domain controller in the forest. It contains information about the Active Directory schema, which in turn defines the different object classes and attributes within Active Directory. Configuration NC Also replicated to every other DC in the forest, this NC contains forest-wide configuration information pertaining to the physical layout of Active Directory, as well as information about display specifies and forest-wide Active Directory quotas.

Domain NC This NC is replicated to every other DC within a single Active Directory domain. This is the NC that contains the most commonly-accessed Active Directory data: the actual users, groups, computers, and other objects that reside within a particular Active Directory domain.

Application Directory Partition is a partition space in Active Directory which an application can use to store that application specific data. This partition is then replicated only to some specific domain controllers. The application directory partition can contain any type of data except security principles (users, computers, groups).

Use the DnsCmd command to create an application directory partition. To do this, use the following syntax:

DnsCmd ServerName /CreateDirectoryPartition FQDN of partition

To create an application directory partition that is named CustomDNSPartition on a domain controller that is named DC-1, follow these steps:

• Click Start, click Run, type cmd, and then click OK.
• Type the following command, and then press ENTER:

dnscmd DC-1 /createdirectorypartition CustomDNSPartition.contoso.com When the application directory partition has been successfully created, the following information appears: DNS Server DC-1 created directory partition: CustomDNSPartition.contoso.com Command completed successfully.

By using replication monitor
go to start > run > type repadmin
go to start > run > type replmon

The global catalog is a distributed data repository that contains a searchable, partial representation of every object in every domain in an Active Directory forest and is stored on domain controllers that have been designated as global catalog servers.