The global catalog is a feature of Active Directory (AD) that allows a domain controller (DC) to provide information on any object in the forest, regardless of whether the object is a member of its domain. Domain controllers with the global catalog feature enabled are referred to as global catalog servers. Show
Core FunctionalityGlobal catalog servers perform several functions, which are especially important in a multi-domain forest environment:
How a Global Catalog WorksActive Directory PartitionsTo understand how the global catalog works, it is important to first understand a little bit about how the Active Directory database is structured. Domain controllers store the Active Directory database in a single file, NTDS.dit. To simplify administration and facilitate efficient replication, the database is logically separated into partitions. Every domain controller maintains at least three partitions:
Domain controllers may also maintain application partitions. These partitions contain information relating to AD-integrated applications and can contain any type of object except for security principals. Application partitions have no specific replication requirements; they are not required to replicate to other domain controllers but can be configured to replicate to any DC in a forest.
You can identify the partitions present on a DC using the following PowerShell cmdlet:
Global Catalog PartitionsConsider a forest that consists of three domains, each with one global catalog server, as depicted below:
As explained earlier, every DC maintains a replica of its local domain partition, the configuration partition and the schema partition. In a multi-domain forest like this one, global catalog servers also host an additional set of read-only partitions, each of which contains a partial, read-only replica of the domain partition from one of the other domains in the forest. It is the information in these partial, read-only partitions that allow global catalog servers to process authentication and forest-wide search requests in a multi-domain forest. The subset of object attributes that are replicated to global catalog servers is called the Partial Attribute Set (PAS). The members of the Partial Attribute Set in a domain can be listed using this PowerShell cmdlet:
In a single-domain forest, all DCs host the only domain partition in the forest; therefore, each one contains a record of all of the objects in the forest and can process authentication and domain service requests.
Active Directory takes advantage of this by allowing any domain controller in a single-domain forest to function as a virtual global catalog server, regardless of whether it has been configured as a global catalog server. The only limitation is that only DCs configured as global catalog servers can respond to queries directed specifically to a global catalog. Deploying Global Catalog ServersWhen a new domain is created, the first DC will be made a global catalog server. To configure additional DCs as global catalog servers, either enable the Global Catalog checkbox in the server’s NTDS Settings properties in the Active Directory Sites and Services management console, or use the following PowerShell cmdlet:
Each site in the forest should contain at least one global catalog server to eliminate the need for an authenticating DC to communicate across the network to retrieve global catalog information. In situations where it is not feasible to deploy a global catalog server in a site (such as a small remote branch office), Universal Group Membership Caching can reduce authentication-related network traffic and allow the remote site’s DC to process local site login requests using cached universal group membership information. This feature requires the remote DC to communicate with a global catalog server to process initial logons and perform search requests. It is recommended that all DCs be configured as global catalog servers unless there is a specific reason to avoid doing so. Senior Technical Product Manager at Netwrix. Kevin is passionate about cyber-security and holds a Bachelor of Science degree in Digital Forensics from Bloomsburg University of Pennsylvania.
What Active Directory partition contains the information needed to define objects and object?The schema partition contains information that defines object classes and attributes used within the domain. It determines what objects can exist within Active Directory, and what attributes each can have.
What are the partitions of Active Directory?There are three native partitions Schema/Configuration/Domain and additionally there is also the Application partition.. Schema information contains - definitional details about objects and attributes that one CAN store in the AD. ... . Configuration information contains - configuration data about forest and trees.. Where are Active Directory objects defined?The Active Directory database (directory) contains information about the AD objects in the domain. Common types of AD objects include users, computers, applications, printers and shared folders. Some objects can contain other objects (which is why you'll see AD described as “hierarchical”).
What is the Active Directory component that contains a reference to all objects with Active Directory called?Domain. A domain in AD is a structural component of the AD network. Domains contain AD objects such as users, printers, computers, and contacts, which may be organized into OUs and groups. Each domain has its own database, and also its own set of defined policies that are applied to all the AD objects within the domain ...
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