What Is Active Directory?

Microsoft created Active Directory as a specialized software solution to help security management teams and administrators of Windows domain networks to manage and deliver network changes, as well as system or security policy modifications to all machines linked to the domain, or to designated subsets of users or endpoints. The first version of Active Directory was published with Windows Server 2000, although the most recent version is compatible with Windows Server 2019.

Network administrators can gain high-level management over a network’s domains, objects, and users by using Active Directory. Administrators can group users, assign or remove security and access privileges depending on group membership, and keep track of access controls at all levels of the company. Network administrators can also deploy changes in an organized and streamlined manner using Active Directory’s unique methodology for structuring network objects, rather than having to change each object individually.

The Active Directory Data Structure: Forests, Trees, and Domains

The hierarchical structure of items in an AD network is defined by forests, trees, and domains. These are the logical divisions that are used to categorize items.

• Domains: Individual items are organized into domains, with each domain’s objects being stored in a single database. The DNS name structure uniquely identifies each domain. A domain is a collection of network objects that are all connected to the same AD database. A domain is a management boundary, which means that the things contained inside it are essentially grouped together to make collective management easier.
• Trees: The trees are the next level of the hierarchy. A tree is a collection of domains and domain trees in a single namespace. Domains that are grouped together in a single tree can be controlled in the same manner that items in a single domain can be managed collectively.
• Forests: Forests are at the top of the Active Directory structure. A forest is a group of trees with the same global catalog, logical structure, directory schema, and configuration. A network administrator can see all of the objects in the directory at the forest level. The forest also acts as a security barrier, ensuring that a network administrator in one forest has no access to items in another and that only things in the forest can be accessed.

Features of Active Directory (Network Objects, Schemas, and Hierarchy)

Users can get information on network objects and endpoints (certification status, authentication status, and so on) as well as services from AD. To comprehend the inner workings of the Active Directory software tool, we must first grasp how the tool defines and treats various network objects.

• Network Objects: Users, groups, laptops, tablets, mobile phones, end-user apps, security applications, printers, and shared folders are all examples of network objects in Active Directory. A type or class is given to a network object, and all network objects in that class have the same set of attributes (but different values for at least one of these attributes). For example, a user’s properties could include First Name and Telephone Number, but a printer’s attributes could include Model Number and IP Address. The properties of each object define it individually.
• Characterization Schema: The characterization schema is the unique identifier associated with each network object. These schemas define how each object in the network will be used. When network administrators make modifications to an active directory schema, the changes are propagated throughout the system automatically.
• Hierarchy: Objects are arranged into hierarchies in the AD framework, which dictate how they can be viewed, who can access them, and how they can be modified by the administrator.

The following are some of the most important AD features and capabilities:

• A worldwide catalog with full information on each object in the directory.
• A query and index system for finding directory information quickly by, administrators, users and applications.
• A directory data replication service that distributes directory data over the network.

The AD schema includes User, Group, Contact, Computer, Shared Folder, Printer, and Organizational Unit objects, as well as a collection of descriptive characteristics for each object. User Object attributes, for example, include information such as the user’s name, phone number, and address.

Other securities and networking protocols used by Active Directory include

• LDAP (Lightweight Directory Access System),
• DNS (Domain Name System), and
• Microsoft’s Kerberos authentication protocol.

What are the Active Directory Domain Services (AD DS)?

Active Directory Domain Services is a set of network services provided by the software (AD DS). Active Directory delivers critical security services in the form of AD DS, in addition to facilitating the management of groups of network objects. Among the services offered are:

• Active Directory Domain Services (AD DS): this is the fundamental AD service that performs user authentication, provides search functionality, manages user-domain interactions, and stores data in a single location.
• Active Directory Rights Management (AD RM): is a term used to describe the process of managing information rights (controlling access permissions to presentations, workbooks, documents, etc.). It protects intellectual property and prevents unauthorized access to or theft of digital content.
• Active Directory Certificate Services (AD CS): is in charge of the generation, monitoring, and distribution of security certificates.
• Active Directory Lightweight Directory Services (AD LDS) – a low-overhead variant of AD DS that supports directory-enabled apps using the LDAP protocol.
• Active Directory Federation Services (AD FS): this enables organizations and corporations to share identity and access management information. It offers single sign-on services to make it easier for users to access web apps.

Advantages of Active Directory

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

• Security – Access to network resources is controlled by Active Directory, which helps enterprises increase security.
• Extensibility – AD 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, lowering operational costs and making management easier.
• Resiliency – To ensure high availability and business continuity, AD supports redundant components and data replication.

Trusts and Active Directory

Trusts are rules in Active Directory that allow users in one domain to access resources in another domain. There are a variety of trust rules that provide users with differing levels of access and rights.

One-way or two-way trusts exist. Users from Domain A can access Domain B, but users from Domain B cannot access Domain A in a one-way trust.

There are two types of trusts: transitive and intransitive. In the forest, a transitive trust can be extended to more than two domains, but an intransitive trust is a one-way trust between only two domains.

A forest trust is one that covers the entire forest, is transitive, and can be one-way or two-way. The network administrator sets the default forest trust boundary, which is applied to all newly created domains automatically.

Final Thoughts

In conclusion, the fundamental Active Directory service is used to verify users’ identities and restrict access to network resources. A domain controller is a server that runs AD DS. For resiliency, most Windows domain networks have two or more domain controllers: one primary and one or more backup domain controllers. Users can authenticate to a domain controller during login and are granted access to specific resources based on administrative policies.