Active Directory (AD)

You could hear someone mention Active Directory. It's sometimes referred to as "AD." Active Directory is a Microsoft software that organizes and makes the information in an operating system's directory accessible. It's a connection between "objects" and "values." That may sound a little "techie," but it's actually rather straightforward.

Here how it’s done:

  1. What is Active Directory?
  2. Active Directory Services
  3. Trusting Terminology
  4. Features of Active Directory Domain Service
  5. Benefits of Active Directory

What is Active Directory?

Active Directory (AD) is a directory service for Windows domain networks developed by Microsoft which comes as a set of processes and services with most Windows Server operating systems. At first, Active Directory was exclusively responsible for domain management. Active Directory, on the other hand, has come to represent a wide range of directory-based identity-related services.

A domain controller is a server that runs the Active Directory Domain Service (AD DS) role. In a Windows domain network, it authenticates and authorizes all users and computers. Creating and enforcing security policies across all computers, as well as installing and updating software.

For example, when a user enters into a Windows domain machine, Active Directory analyses the submitted password and decides if the user is a system administrator or a regular user. It also enables for information management and storage, as well as authentication and authorization processes, and other related services such as Certificate Services, Active Directory Federation Services, Lightweight Directory Services, and Rights Management Services are all built on top of this framework.

Active Directory Services

Multiple directory services are included in Active Directory Services. Active Directory Domain Services, sometimes known as AD DS or just AD, is the most well-known.

  • Domain Services

Every Windows domain network is built on the foundation of Active Directory Domain Services (AD DS). It keeps track of domain members, such as devices and users, verifies their credentials, and establishes their access privileges.

This service is run by a domain controller, which is a server. When a user signs into a device, connects to another device over the network or runs a line-of-business Metro-style app on the device. Domain Services is used or relied on by other Active Directory services and most Microsoft server technologies.

Encrypting File System, BitLocker, Domain Name Services, Remote Desktop Services, Exchange Server, and SharePoint Server are just a few examples. Self-managed AD DS should not be confused with Azure AD DS, which is a cloud-based service.

  • Lightweight Directory Services

Active Directory is a directory service that allows you to Active Directory Application Mode (ADAM), formerly known as Lightweight Directory Services (AD LDS), is an LDAP protocol implementation for AD DS. On Windows Server, AD LDS runs as a service. It includes a Data Store for directory data storage as well as a Directory Service with an LDAP Directory Service Interface. Multiple AD LDS instances, unlike AD DS, can run on the same server.

  • Certificate Services

On-premises public key infrastructure is created using Active Directory Certificate Services (AD CS). It may generate, validate, and revoke public key certificates for an organization's internal use. Files (when used with Encrypting File System), emails (per the S/MIME standard), and network traffic (when used by virtual private networks, Transport Layer Security protocol or IPSec protocol) can all be encrypted with these certificates.

Although AD CS predates Windows Server 2008, it was previously known as Certificate Services.

  • Federation Services

Active Directory Federation Services (AD FS) is a single sign-on service for Active Directory users. Users can utilize several web-based services (e.g., internet forum, blog, online shopping, webmail) or network resources with only one set of credentials kept centrally, rather than having to be issued a separate set of credentials for each service, with an AD FS infrastructure in place.

The goal of AD FS is to extend the functionality of AD DS, which allows users to authenticate with and use devices on the same network using a single set of credentials. They can utilize the same set of credentials in a different network with the former. AD FS is built on the concept of federated identification, as the name suggests.

  • Rights Management Services

Before Windows Server 2008, Active Directory Rights Management Services (AD RMS) were known as Rights Management Services or RMS. It is a server software for managing information rights that comes with Windows Server. It restricts access to documents such as corporate e-mails, Microsoft Word documents, and websites and the actions that authorized users are allowed to carry out on them using encryption and a sort of selective capability denial.

Trusting Terminology

Trusts are used by Active Directory to control resource access privileges between domains. Trusts come in several different types:

  • One-way Trust
    When a first domain grants access privileges to users on a second domain, this is known as a one-way trust. The second domain, on the other hand, does not allow users from the first domain to access it.
  • Two-way Trust
    When there are two domains, each of which enables access to users from the other domain, this is known as a two-way trust.
  • Trusted Domain
    A trusted domain is a single domain that grants users access to a second domain.
  • Transitive Trust
    A transitive trust can span more than two domains and grant access to other trusted domains in the forest.
  • Intransitive Trust
    A one-way trust that is limited to two domains is known as an intransitive trust.
  • Explicit Trust
    A network admin creates an explicit trust, which is a one-way, nontransitive trust.
  • Cross-link Trust
    A sort of explicit trust is a cross-link trust. Cross-link trusts exist between domains that are either in the same tree, with no child-parent relationship, or in distinct trees.
  • Forest Trust
    A forest trust can be one-way, two-way, or transitive, and it can apply to domains within the entire forest.
  • Shortcut
    A shortcut connects two domains from different trees. One-way, two-way, and transitive shortcuts are all possible.
  • Realm
    A realm is a one-way or two-way trust that might be transitive, intransitive or both.
  • External Trust
    An external trust is a trust that connects domains from other forests or non-AD domains. External trusts can be one-way or two-way, nontransitive or transitive.
  • Private Access Management (PAM) Trust
    A one-way trust is a private access management trust. Between a production forest and a bastion forest, Microsoft Identity Manager creates it.

Features of Active Directory Domain Service

To coordinate networked pieces, Active Directory Domain Services uses a tiered structure consisting of domains, trees, and forests.

  • Domain
    A domain is a collection of things that share the same Active Directory database, such as users or devices. The domain name system (DNS) is a system that organizes domains.
  • Tree
    One or more domains are grouped together to form a tree. A continuous namespace is used to organize the collection of domains into a logical hierarchy in the tree structure. Trees can be considered as trust relationships in which two domains share a secure connection, or trust. Multiple domains can be trusted, with one trusting the other and the second trusting the third. The first domain can implicitly trust the third domain due to the hierarchical nature of this system.
  • Forest
    A forest is a collection of trees. A forest is made up of catalogs, directory schemas, application data, and domain configurations that are all shared. In a forest, the schema defines an object's class and attributes. Furthermore, global catalog servers keep track of all the objects in a forest. The forest is Active Directory's security border, according to Microsoft.
  • Organizational Units
    Users, groups, and devices are organized under Organizational Units (OUs). Each domain is allowed to have its own OU. However, because each user or item in a domain must be unique, OUs cannot have separate namespaces.
  • Containers
    Containers are comparable to organizational units (OUs), except GPOs cannot be applied to or linked to container objects.

Benefits of Active Directory

Active Directory offers a number of functional and business advantages, including the following:

  • Security – Access to network resources is controlled by Active Directory, which helps enterprises increase security.
  • Extensibility - Active Directory data may be easily organized to correspond with an organization's structure and business demands.
  • Simplicity — Administrators can manage user identities and access privileges across the enterprise from a single location, making management easier and lowering operational costs.
  • Resiliency — To ensure high availability and business continuity, Active Directory enables redundant components and data replication.


Active Directory is a widely used directory service. It aids in the organization of your company's users, computers, and other assets. Your company's full hierarchy is organized using AD, from which PCs belong on which network to what your profile picture looks like and which users have access to the storage area.

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Janani works for Atatus as a Content Writer. She's devoted to assisting customers in getting the most out of application performance monitoring (APM) tools.

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