Updates to the < domain > container are replicated only to all Domain Controllers within the AD DOMAIN and to Global Catalog servers if the update is made to an attribute that is marked for replication (Partial Attribute Set) to the Global Catalog.
Global Catalog Domain Controllers contain the Partial Attribute Set of Domain Directory Partition for each AD DOMAIN within the AD Forest
Each AD DOMAIN can have multiple Domain Controllers and a AD Forest can have multiple AD DOMAINs.
Each Domain Controller stores a full replica of the Domain Directory Partition for the AD DOMAIN that it is a member, but does not store replicas of the Domain Directory Partitions for other AD DOMAINs within the AD Forest.
The Directory Partition Hierarchy can be viewed in the Active Directory Domains and Trusts console, where trust relationships between domains can be managed.
Active Directory Users and Computers obtains it data from this partition.