11 – Microsoft Active Directory Administration Fundamentals: Deploying Enterprise Identity with Windows Server 2025

Active Directory | Windows Server | PowerShell | Identity Administration | Enterprise Security

Overview

After developing a solid understanding of Windows Server administration through PowerShell, the next logical step was to introduce the identity infrastructure that underpins the vast majority of Microsoft enterprise environments.

This laboratory focused on deploying Active Directory Domain Services (AD DS), transforming a standalone Windows Server installation into a fully functioning Domain Controller capable of providing authentication, authorisation and centralised identity management.

Unlike the previous laboratory, which concentrated on understanding the operating system itself, this exercise marked the transition into enterprise identity administration. It demonstrated how Windows Server evolves from an independent system operating within a WORKGROUP into the foundation of an organisational identity infrastructure.

Although many organisations are adopting cloud-first strategies through Microsoft Entra ID and Microsoft 365, Active Directory continues to play a critical role across hybrid enterprise environments. Understanding how Active Directory functions remains fundamental for systems administrators, identity engineers, security analysts and cloud professionals responsible for managing authentication, access control and identity lifecycle processes.

This laboratory therefore represents a significant milestone in my Microsoft infrastructure journey, establishing the on-premises identity platform that will support future work involving Group Policy, organisational units, hybrid identity and Microsoft Entra ID integration.

Objectives

The objectives of this laboratory were to:

Install Active Directory Domain Services.
Promote Windows Server 2025 to a Domain Controller.
Create a new Active Directory forest.
Configure Active Directory-integrated DNS.
Validate successful domain and forest creation.
Verify Domain Controller functionality.
Confirm FSMO role ownership.
Validate Active Directory services.
Test DNS functionality and service discovery.
Explore default Active Directory users and security groups.
Review security-related server configuration.
Continue collecting PowerShell-based evidence for reproducible administration.

Rather than relying on graphical tools alone, PowerShell remained the primary administration and validation interface throughout the exercise, reinforcing an evidence-based approach to enterprise system administration.

Environment and Configuration

The laboratory continued using the virtual infrastructure established during the previous Windows Server administration exercises.

Component	Configuration
Virtualisation Platform	Oracle VirtualBox
Host Operating System	Windows 11
Guest Operating System	Windows Server 2025 Standard Evaluation
Administration Method	Windows PowerShell
Computer Name	WIN-URRN4NJRE9I

Before introducing Active Directory, the server operated as a standalone Windows Server within a WORKGROUP configuration.

This provided a clean baseline from which the complete identity infrastructure could be deployed and validated.

Unlike previous exercises, this laboratory introduced services that fundamentally changed the role of the server within the environment.

Key Activities Performed

1. Environment Validation

Before making any infrastructure changes, the PowerShell environment was validated to ensure the correct administrative tools were available.

PowerShell version information confirmed that Windows PowerShell 5.1 was being used, ensuring compatibility with Windows Server administration modules such as ServerManager and the Active Directory PowerShell module.

The server identity was also verified to confirm that administration was being performed inside the Windows Server virtual machine rather than on the Windows 11 host operating system.

Although this validation required only a few commands, it reinforced an important administrative principle: always confirm the environment before making infrastructure changes.

2. Installing Active Directory Domain Services

The next stage involved verifying that the Active Directory Domain Services role was available before installation.

PowerShell confirmed that the feature was present but not yet installed, allowing the deployment to proceed.

The AD DS role was then installed together with its management tools.

At this stage, the server had not yet become a Domain Controller.

Instead, Windows Server simply acquired the software components required to support enterprise identity services.

This distinction is important because installing Active Directory binaries alone does not create a domain or provide authentication services.

Those capabilities become available only after the server is promoted to a Domain Controller.

3. Domain Controller Promotion

Following installation of Active Directory Domain Services, the server was promoted to become the first Domain Controller within a newly created Active Directory forest.

A new forest named corp.lab was created using PowerShell.

During the promotion process, Windows Server automatically configured several essential infrastructure components, including:

Active Directory Domain Services
Domain Controller functionality
Active Directory-integrated DNS
Global Catalog services
SYSVOL replication structure
Kerberos authentication
Enterprise identity services

Following successful completion of the promotion process, Windows Server restarted automatically.

This marked the most significant architectural change performed during the laboratory.

The server transitioned from operating as an independent machine into the central identity authority responsible for authenticating users, computers and services across the domain.

4. Validating the Active Directory Domain

After reboot, the authentication environment immediately reflected the successful deployment.

Instead of logging on using the local administrator account, Windows now presented the domain-based CORP\Administrator account.

PowerShell validation confirmed that:

the corp.lab domain had been successfully created
the Active Directory database structure existed
Windows Server 2025 domain functional level had been established
domain naming information was correctly configured

Rather than assuming success after installation, every configuration change was independently verified using PowerShell.

This reflects professional enterprise administration, where validation is considered just as important as implementation itself.

5. Forest and Domain Controller Validation

Once the domain had been confirmed, the wider Active Directory forest configuration was examined.

Validation demonstrated that:

the forest name was correctly configured
the Windows Server 2025 forest functional level had been established
the Global Catalog was operational
the Schema Master role had been assigned correctly
the Domain Controller had been successfully registered

Additional validation confirmed that the server was operating as a writable Domain Controller with Global Catalog functionality enabled.

PowerShell also verified the fully qualified domain name and correct IPv4 addressing, confirming that the identity infrastructure had been deployed successfully and was operating as expected.

6. Flexible Single Master Operations (FSMO) Role Validation

One of the most important validation stages involved confirming ownership of the Flexible Single Master Operations (FSMO) roles.

Although Active Directory is a distributed directory service, certain operations must be performed by designated Domain Controllers to maintain consistency across the forest and domain.

PowerShell confirmed that all five FSMO roles had been successfully assigned to the newly promoted Domain Controller.

These included:

Schema Master
Domain Naming Master
PDC Emulator
RID Master
Infrastructure Master

This configuration is expected within a single-domain laboratory environment where only one Domain Controller exists.

Understanding FSMO roles provides valuable insight into how Active Directory maintains consistency, manages object creation and supports enterprise-scale identity administration.

7. Validating Core Active Directory Services

Following Domain Controller deployment, several critical Windows services were validated to ensure the identity infrastructure was fully operational.

PowerShell confirmed that the following services were running successfully:

Active Directory Domain Services (NTDS)
DNS Server
Kerberos Key Distribution Center (KDC)
Netlogon

Each service performs an essential role within the authentication process.

The NTDS service hosts the Active Directory database, storing directory objects and supporting authentication requests.

DNS enables clients to locate Domain Controllers and other directory services.

The Kerberos Key Distribution Center issues authentication tickets that enable secure identity verification across the domain.

Netlogon maintains secure communication channels between domain members and the Domain Controller.

Validating these services confirmed that the newly deployed identity infrastructure was functioning correctly and ready to support enterprise authentication.

8. Replication and DNS Validation

Although the laboratory environment consisted of only a single Domain Controller, replication health was still verified.

PowerShell reported no replication failures, confirming that the directory database was operating normally for the current topology.

The next stage focused on Domain Name System (DNS), one of the most critical dependencies within Active Directory.

Unlike standalone Windows systems, Active Directory relies heavily on DNS to locate services rather than simply resolving hostnames.

Validation confirmed successful hostname resolution for the Domain Controller.

Further testing verified the registration of LDAP Service (SRV) records, demonstrating that clients could automatically discover Domain Controllers through DNS.

This stage reinforced an important concept often overlooked by newcomers to Active Directory:

Without correctly functioning DNS, Active Directory cannot operate reliably.

Rather than being separate technologies, DNS and Active Directory work together as tightly integrated components of Microsoft’s enterprise identity architecture.

9. Exploring Active Directory Objects

With the infrastructure successfully deployed, attention shifted towards examining the directory itself.

PowerShell was used to review the default user accounts created during forest deployment.

These included:

Administrator
Guest
krbtgt

Although only a small number of accounts existed at this stage, each performs a specific role within Active Directory.

The Administrator account provides domain-level administrative control.

The Guest account represents a disabled, highly restricted identity.

The krbtgt account plays a particularly important role, acting as the Kerberos service account responsible for generating authentication tickets throughout the domain.

The laboratory also examined the default Active Directory security groups.

Examples included:

Domain Admins
Enterprise Admins
Schema Admins
Domain Users
Domain Computers
Domain Controllers
DnsAdmins
Protected Users

Understanding these built-in groups is fundamental for implementing least privilege, delegated administration and role-based access control throughout enterprise environments.

10. Security Validation

The final stages of the laboratory focused on validating the security posture of the newly deployed Domain Controller.

Windows Firewall profiles remained enabled across Domain, Private and Public networks, ensuring that the introduction of Active Directory services had not weakened the server’s security configuration.

Recent Windows Security events were also examined using PowerShell.

The logs confirmed normal authentication activity, including:

Successful logon events
Privileged administrator logons
User logoff events

These events provide the operational telemetry relied upon by Security Operations Centres, SIEM platforms and Detection Engineering teams when monitoring authentication behaviour.

Although this laboratory concentrated on infrastructure deployment, it also demonstrated how security monitoring begins with understanding normal system behaviour.

Building familiarity with expected authentication events establishes the foundation required for detecting anomalies in future identity-focused investigations.

Operational Interpretation

This laboratory represents a significant transition within the overall learning journey.

Previous exercises focused on understanding Windows Server as an operating system.

This laboratory transformed that standalone server into an enterprise identity platform capable of supporting authentication, authorisation and centralised identity management.

The progression can now be viewed as:

Windows Server

↓

Active Directory Domain Services

↓

Enterprise Identity

↓

Hybrid Identity

↓

Microsoft Entra ID

↓

Cloud Security

Each layer builds directly upon the previous one.

Understanding how Active Directory operates internally provides essential context for future work involving Microsoft Entra ID synchronisation, hybrid identity, privileged access management and cloud security operations.

Key Learning Outcome

This laboratory demonstrated that deploying Active Directory extends far beyond installing another Windows Server role.

Successful enterprise identity administration requires systematic validation of every component involved in the authentication process.

Using PowerShell throughout the exercise reinforced several important principles:

Validate before assuming success.
Collect repeatable administrative evidence.
Confirm infrastructure health after every major configuration change.
Understand how authentication depends upon supporting services such as DNS and Kerberos.
Treat infrastructure administration as a security responsibility rather than simply a configuration task.

The experience also highlighted how tightly integrated Microsoft’s enterprise technologies are, with Windows Server, Active Directory, DNS and authentication services working together to provide secure identity management.

Conclusion

This laboratory successfully transformed a standalone Windows Server 2025 installation into a fully operational Active Directory Domain Controller.

Through PowerShell-based administration and systematic validation, the deployment confirmed successful installation of Active Directory Domain Services, creation of a new forest and domain, DNS integration, FSMO role assignment, Domain Controller functionality and core identity services.

Beyond the technical deployment itself, the laboratory reinforced the importance of evidence-based administration, demonstrating how validation and documentation are integral components of professional infrastructure management.

This exercise establishes the foundation for future laboratories involving Organisational Units, Group Policy, delegated administration, hybrid identity, Microsoft Entra ID integration and identity security monitoring.

Repository Context

This laboratory forms part of:

Phase 2 — Microsoft Infrastructure Administration Foundations

Laboratory: 2.3 Active Directory Administration Fundamentals

Portfolio progression:

Windows Infrastructure

↓

Windows Administration

↓

Active Directory

↓

PowerShell Administration

↓