Microsoft Active Directory – A Quick Beginner’s Guide

Active Directory Domain Services (AD DS) is Microsoft’s on-premises directory service. It acts as a centralized database that stores information about users, computers, groups, and other network resources while handling authentication and authorization across Windows networks.

Why Active Directory is Important

It provides centralized management, single sign-on, Group Policy enforcement, and secure access control for users and devices in an organization.

Key Components

• Forest – The highest security boundary
• Domain – The main administrative unit
• Organizational Unit (OU) – Used to organize objects and apply Group Policy
• Domain Controller – The server that authenticates users and stores the AD database

What Active Directory Does

• Authenticates users using Kerberos
• Controls who can access network resources
• Enforces security and configuration policies through Group Policy
• Provides single sign-on for domain-joined devices

Quick Setup Overview

1. Install the Active Directory Domain Services role on Windows Server
2. Promote the server to a Domain Controller
3. Create your domain (example: corp.company.local)
4. Create users, groups, and Organizational Units

Active Directory vs Microsoft Entra ID

• Active Directory – On-premises (Kerberos, Group Policy, domain join)
• Microsoft Entra ID – Cloud identity (OAuth, Conditional Access, Microsoft 365)

Most organizations today run a hybrid environment using both Active Directory and Microsoft Entra ID.

Pro Tip: Always deploy at least two domain controllers for high availability and redundancy.