What is Active Directory? Complete Guide for Beginners

Active Directory sits behind a huge amount of day-to-day work in IT. If you manage users, laptops, file shares, permissions, or Windows policies, you bump into AD constantly.

This guide walks you through what Active Directory is, how it works, and what the core terms actually mean in practice. 

You’ll also see how AD compares with Microsoft Entra ID and which tools help you manage it.

What is Active Directory? 

Active Directory (AD) gives an organization one central place to manage people, computers, and access. Instead of creating accounts separately on every laptop, server, and app, you create identities once, then you control what those identities can do across the network.

If you run IT for more than a handful of users, you almost always want a system that can answer questions like:

• Who are you?
• What device do you use?
• What do you have permission to access?
• Which security rules must your device follow?

Active Directory answers these questions.

Why Active Directory Exists

locations. Devices come and go, apps change, and security requirements tighten. When you manage all of that manually, chaos shows up quickly:

• Users forget passwords and lock themselves out. 
• People keep access after role changes. 
• Devices drift from security settings. 
• IT spends days on repetitive account work.

Active Directory solves this by creating a shared system of record for identity and access on Windows networks (and beyond, with the right integrations). You set rules once, then you apply them across thousands of endpoints.

What Active Directory Actually Manages

AD stores “directory data” about things on your network. In AD language, those “things” become objects.

Common AD objects include:

• User accounts (employees, contractors, interns) 
• Groups (Sales, IT Admins, Finance Approvers) 
• Computers (laptops, desktops, servers) 
• Printers 
• Shared folders and resources 
• Service accounts that apps use 
• Policies and configuration settings

Each object includes attributes. A user object might include a display name, email address, job title, phone number, manager, department, and group memberships. A computer object might include a hostname, an operating system, and the last sign-in.

Admins use these attributes constantly. You might filter users by department, apply policies to a certain office, or grant access based on team membership. 

Common Active Directory tasks admins handle 

Even if you never become the AD person within your organization, you will run into these workflows:

• Create users, set attributes, and assign group membership 
• Reset passwords and unlock accounts 
• Join computers to the domain 
• Move objects into the correct OUs (Organizational Units) 
• Apply GPOs (Group Policy Object) for security settings and configuration 
• Create file share permissions using groups 
• Configure delegation for helpdesk and other teams 
• Maintain DC health, patching, and replication

PowerShell can speed up almost all of this. When you need to create 300 users, you probably do not want to click through a GUI (Graphical User Interface) all day. You want scripts that run safely and predictably.

PowerShell is a task automation and configuration management framework developed by Microsoft that combines a command-line shell with a scripting language. IT admins use it to manage Windows, Microsoft 365, Azure, and other systems through commands and scripts. 

Key Active Directory Components You Should Know 

1. Active Directory Domain Services 

Most people mean Active Directory Domain Services (AD DS) when they say “Active Directory.” AD DS runs the core directory: identities, authentication, authorization, and policy. 

When your organization runs AD DS, you usually operate:

• A domain 
• Domain controllers 
• DNS that supports AD 
• Group Policy 

2. Domain Controllers 

A domain controller (DC) runs the directory database and handles sign-ins. When a user logs in to a Windows device joined to the domain, the device talks to a DC to verify identity and retrieve access info. 

Domain Controllers also:

• Enforce password policies 
• Issue Kerberos tickets for single sign-on 
• Store and replicate directory changes 
• Help apply Group Policy

You typically run multiple Domain Controllers so the directory keeps working when a server fails or a site loses connectivity.

3. The Directory Database

AD stores directory data in a database called NTDS.dit (New Technology Directory Services). Domain Controllers keep a copy of that database, and sync changes through replication. 

You never edit this database directly. You use tools like Active Directory Users and Computers, PowerShell, or LDAP-based tools to make changes safely. LDAP stands for Lightweight Directory Access Protocol. 

Active Domain Hierarchy 

AD uses a hierarchy. People hear these terms and panic a bit, but the terms sound heavier than they feel. Let’s review its hierarchy in more detail.

Domain

A domain groups objects under one administrative boundary. It also provides a shared identity space. When a user signs in with a username like jane@company.com, the domain handles that identity. 

A domain also defines:

• Password and account policies (with some important nuance) 
• Trust relationships with other domains 
• Administrative scope for many tasks 

Organizational units 

An organizational unit (OU) groups objects to support delegation and policy application. For example, you might create OUs for:

• Workstations 
• Servers 
• Users 
• Departments 
• Locations

Admins link Group Policy Objects (GPOs) to OUs. That link lets you apply settings to only the objects inside that OU. You can also delegate control. Maybe helpdesk can reset passwords in the “Users” OU but cannot touch servers.

Tree

A tree groups one or more domains in a contiguous DNS namespace. For example:

• corp.example.com 
• sales.corp.example.com 

Forest

A forest sits at the top. It can contain multiple trees and domains. The forest shares:

• A schema 
• A global catalog 
• Trust between domains 
• Forest-wide configuration

In practice, the forest acts as the ultimate security boundary. Many security decisions start with, “Do we trust this forest?” 

Active Directory vs Entra ID: What’s the Difference? 

Think of Active Directory as your on-prem identity system for Windows networks. It runs on Windows Server, talks Kerberos, and powers domain logins, file shares, printers, and Group Policy.

When your org relies on classic Windows infrastructure, AD sits right in the middle of it. 

Microsoft Entra ID (formerly Azure AD) focuses on cloud identity. It signs users into Microsoft 365 and thousands of SaaS apps, supports modern auth (like OAuth 2.0 and OpenID Connect), and pairs naturally with Conditional Access and MFA. 

It also handles cloud-first device identity through Entra join and works closely with Intune for device controls. 

A lot of organizations use both. AD handles on-prem domain needs, while Entra ID handles cloud apps and remote access policies.

Then, tools like Microsoft Entra Connect or Entra Cloud Sync link identities, so users can use the same set of credentials across both worlds. 

3 Top Active Directory Management Tools 

1. CiraSync 

CiraSync is a top Active Directory management tool. handles a gap that shows up in almost every AD or Microsoft 365 environment: employees need the Global Address List on their phones, not stuck behind search. 

As mentioned earlier, organizations commonly use Active Directory and Entra ID. Admins sync AD data to Entra ID, connect CiraSync to Entra AD, and pick what contact lists or shared calendars to sync. 

CiraSync then pushes updates to iOS and Android devices, keeping names, numbers, and titles up to date automatically. You cut contact tickets and keep directory data consistent across mobile devices.

2. ManageEngine ADManager Plus 

ManageEngine ADManager Plus speeds up everyday Active Directory work when you feel tired of clicking. You provision and deprovision users, manage groups, move objects, reset passwords, and run bulk updates from one console. 

Then you pull reports to find stale accounts, risky permissions, and cleanup tasks you keep postponing. It supports delegation and approval workflows, so helpdesk can handle routine changes without full admin power.

ADManager Plus also covers Microsoft 365 tasks and scheduled automations. You can export reports for audits too.  

3. One Identity Active Roles 

One Identity Active Roles puts guardrails around AD administration, especially when many people touch the directory. You set policies for user and group changes, then you run actions through workflows and approvals so admins follow the same rules. 

Active Roles tracks change history and supports role-based delegation, which helps you limit who can change privileged objects. 

Teams often choose it for hybrid environments that include AD and Entra ID, plus audits that demand clear accountability. It also offers web interfaces for delegated admin work. 

To Sum Up 

Active Directory gives you structure. It turns identity, access, and device control into something you can manage without endless manual work.

Once you understand domains, domain controllers, groups, and Group Policy, a lot of “random” IT issues start looking less random. 

Then Entra ID adds the cloud layer for modern sign-ins and SaaS access, and many teams run both side by side. If you treat AD like core infrastructure and keep security tight, you make everything else in your environment easier to run. 

Frequently Asked Questions