Active Directory
Active Directory is a directory service developed by Microsoft that centralizes identity, authentication, authorization, and policy management in enterprise networks.
What is Active Directory?
Active Directory (AD) is a directory service that allows organizations to centrally manage users, computers, groups, and resources within a network. It provides authentication, authorization, and policy enforcement for Windows-based environments.
Active Directory is a core component of Microsoft Windows Server infrastructures.
Why Active Directory matters
Active Directory is critical because it:
- Centralizes identity and access management
- Enables secure authentication across the network
- Simplifies administration at scale
- Enforces security and configuration policies
- Serves as the backbone of enterprise IT environments
Most enterprise Windows networks rely on Active Directory.
Core components of Active Directory
Active Directory is built around several key elements:
- Domain - logical boundary for identities and policies
- Domain Controller (DC) - server hosting AD services
- Objects - users, computers, groups, printers
- Organizational Units (OUs) - structure and delegation
- Schema - defines object types and attributes
These components enable scalable and structured management.
How Active Directory works
Active Directory relies on multiple technologies:
- Kerberos for authentication
- LDAP for directory queries
- DNS for service discovery
- Group Policy for configuration enforcement
Together, they provide secure and centralized control.
Authentication and authorization
Active Directory handles:
- User logons to domain-joined devices
- Access to file shares, applications, and services
- Group-based permissions and role management
- Single Sign-On (SSO) within the domain
Credentials are validated by domain controllers.
Group Policy (GPO)
Group Policy Objects (GPOs) allow administrators to:
- Enforce security settings
- Configure operating systems and applications
- Deploy scripts and software
- Standardize user and device behavior
GPOs are a powerful feature of Active Directory.
Active Directory and time synchronization
Active Directory is time-sensitive:
- Kerberos authentication requires synchronized clocks
- Domain controllers rely on NTP
- Time drift can cause authentication failures
Accurate time is mandatory for AD reliability.
Active Directory in modern environments
Active Directory is commonly used alongside:
- Cloud identity platforms
- Hybrid identity architectures
- Endpoint management solutions
- Zero Trust access models
Many organizations run hybrid AD environments.
Security considerations
From a security standpoint:
- Domain controllers are high-value targets
- Misconfigured permissions can enable privilege escalation
- Legacy protocols increase attack surface
- Credential theft can impact the entire domain
Hardening and monitoring Active Directory is essential.
Common misconceptions
- "Active Directory is just a user database"
- "Active Directory is obsolete in the cloud era"
- "AD only works on Windows clients"
- "Active Directory security is automatic"