Schema Master (scope: Enterprise)

Used to introduce manual and programmatic schema updates, and this includes those updates that are added by Windows ADPREP /FORESTPREP, by Microsoft Exchange, and by other applications that use Active Directory Domain Services (AD DS).
Must be online when schema updates are performed.

Domain Naming Master (scope: Enterprise)

Used to add and to remove domains and application partitions to and from the forest.
Must be online when domains and application partitions in a forest are added or removed.

Primary Domain Controller (scope: Domain)

Receives password updates when passwords are changed for the computer and for user accounts that are on replica domain controllers.
Consulted by replica domain controllers that service authentication requests that have mismatched passwords.
Default target domain controller for Group Policy updates.
Target domain controller for legacy applications that perform writable operations and for some admin tools.
Must be online and accessible 24 hours a day, seven days a week.

RID (scope: Domain)

Allocates active and standby RID pools to replica domain controllers in the same domain.
Must be online for newly promoted domain controllers to obtain a local RID pool that is required to advertise or when existing domain controllers have to update their current or standby RID pool allocation.

Infrastructure Master

Updates cross-domain references and phantoms from the global catalog.(scope: Domain)
A separate infrastructure master is created for each application partition including the default forest-wide and domain-wide application partitions created by Windows Server 2003 and later domain controllers. (scope: Application)

The Windows Server 2008 R2 ADPREP /RODCPREP command targets the infrastructure master role for default DNS application in the forest root domain. The DN path for this role holder is CN=Infrastructure,DC=DomainDnsZones,DC=<forest root domain>,DC=<top level domain> and CN=Infrastructure,DC=ForestDnsZones,DC=<forest root domain>,DC=<top level domain>.

	Created by kamsz over 10 years ago

Microsoft 70-410 (Active Directory) Note on Active Directory Flexible Single-Master, created by kamsz on 08/13/2013.

Active Directory Flexible Single-Master