AD DS and Exchange Server Integration
A domain partition contains all objects in the domain’s directory. Domain objects replicate to every domain controller in the domain, and include user and computer accounts and groups.
A subset of the domain partition replicates to all domain controllers in the forest that are global catalog servers. If you configure a domain controller as a global catalog server, it contains a complete copy of its own domain’s objects and a subset of attributes for every domain’s objects in the forest.
The configuration partition contains configuration information for AD DS and applications, including Active Directory site and site link information. In addition, some distributed applications and services store information in the configuration partition. This information replicates through the entire forest, so that each domain controller retains a replica of the configuration partition.
When application developers choose to store application information in the configuration partition, the developers do not need to create their own mechanism to replicate the information. The configuration partition stores each type of configuration information in separate containers. A container is an Active Directory object, similar to an organizational unit (OU) that is used to organize other objects.
The schema partition contains definition information for all object types and their attributes that you can create in AD DS. This data is common to all domains in the forest, and AD DS replicates it to all domain controllers in the forest. However, only one domain controller in the Active Directory forest maintains a writable copy of the schema. By default, this domain controller, known as the Schema Master, is the first domain controller installed in an Active Directory forest.
An administrator can create application partitions manually, and an application can create partitions automatically during its installation process. Application partitions contain specific application data that the application requires. The main benefit of application partitions is replication flexibility. You can specify the domain controllers that contain a replica of an application partition, and these domain controllers can include a subset of domain controllers throughout the forest. Exchange Server 2016 does not use application partitions to store information.
Exchange Server 2016 and AD DS partitions integration
To ensure proper placement of Active Directory components in relation to computers that are running Exchange Server, you must understand how Exchange Server 2016 communicates with AD DS and uses Active Directory information to function. AD DS stores most Exchange Server 2016 configuration information.
An Exchange Server organization and an Active Directory forest have a one-to-one relationship. You cannot have an Exchange Server organization that spans multiple Active Directory forests. You also cannot have multiple Exchange Server organizations within a single Active Directory forest.
Note: In Exchange Server 2016, you also can add an Office 365 domain to the Exchange Admin Center console. This enables you to manage multiple organizations from a single management console.
The Exchange Server 2016 installation process modifies the schema partition to enable the creation of Exchange Server–specific objects. The installation process also adds Exchange Server–specific attributes to existing objects. For example, the installation process updates user objects with additional attributes to describe storage quotas and mailbox features.
Additional Reading: For more information, refer to Exchange 2016 Active Directory schema changes: http://aka.ms/i60f20
The configuration partition stores configuration information for the Exchange Server 2016 organization. Because AD DS replicates the configuration partition among all domain controllers in the forest, configuration of the Exchange Server 2016 organization replicates throughout the forest. The configuration partition includes Exchange Server configuration objects, such as global settings, email address policies, transport rules, and address lists.
The domain partition contains information about recipient objects. This includes mailbox-enabled users, and mail-enabled users, groups, and contacts. Objects that are mailbox-enabled or mail-enabled have preconfigured attributes, such as email addresses.
When you install Exchange Server 2016, the email attributes for mail-enabled and mailbox-enabled objects replicate to the global catalog. In the context of Exchange Server, global catalog is used as follows:
· The global address list (GAL) is generated from the recipients list in an Active Directory forest’s global catalog.
· Exchange Server 2016 transport service accesses the global catalog to find the location of a recipient mailbox when delivering messages.
· Client access services access the global catalog server to locate the user Mailbox server and to display the GAL to Office Outlook, Outlook on the web, or Exchange ActiveSync clients.
Note: Because of the importance of the global catalog in an Exchange Server organization, you must deploy at least one global catalog server in each Active Directory site that contains an Exchange 2016 server. You must deploy enough global catalog servers to ensure adequate performance. We recommend deploying one Active Directory global catalog processor core for every eight mailbox server processor cores that are handling active load. Exchange Server 2016 does not use read-only domain controllers (RODCs) or RODCs that you configure as global catalog servers. This means that you should not deploy an Exchange 2016 server in any site that contains only RODCs or RODCs configured as global catalog servers.