Additional Domain Controller (ADC) Configuration
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Additional Domain Controller (ADC) Configuration
Overview
An Additional Domain Controller (ADC) is a secondary domain controller that joins an existing Active Directory forest. It provides redundancy, load balancing, and fault tolerance for authentication and directory services.
This guide explains how to install and configure an ADC on a Windows Server, joining it to the existing forest.
1. Prerequisites
Before installing the ADC, ensure the following:
- The Primary Domain Controller (PDC) is reachable on the network.
- The ADC server has a static IP address configured.
- DNS settings:
* Primary DNS → IP address of the PDC * Secondary DNS → IP address of the ADC itself
- Both servers have proper time synchronization.
2. Install Active Directory Domain Services (AD DS) and DNS
Step 1: Add Roles and Features
1. Open the Server Manager and click on Add Roles and Features. 2. Choose Role-based or feature-based installation → click Next. 3. Select the local server → click Next. 4. Select the following roles:
* Active Directory Domain Services (AD DS) * DNS Server
5. When prompted, click Add Features on the pop-up window. 6. Click Next until you reach the installation screen. 7. Click Install. 8. Wait for installation to complete and click Close.
3. Promote the Server to an Additional Domain Controller
Step 1: Launch Post-Installation Tasks
1. In Server Manager, click the notification flag → select Promote this server to a domain controller. 2. Choose Add a domain controller to an existing domain. 3. Enter the domain name (for example: example.local). 4. Click Select to browse and connect to the existing forest’s PDC. 5. Authenticate with domain administrator credentials and click Next.
Step 2: Domain Controller Options
1. Ensure the following options are selected:
* Domain Name System (DNS) Server * Global Catalog (GC)
2. Enter a Directory Services Restore Mode (DSRM) password. 3. Click Next.
Step 3: Replication Settings
1. From the list, select the Primary Domain Controller (PDC) to replicate from. 2. Click Next.
Step 4: Paths and Configuration
1. Accept the default database, log, and SYSVOL folder paths. 2. Click Next.
Step 5: Review and Install
1. Review all configuration details. 2. Click Install. 3. The server will automatically restart after installation completes.
4. Post-Installation Verification
After the ADC installation and reboot:
1. Log in using domain credentials. 2. Open Server Manager → Tools → Active Directory Users and Computers to confirm successful domain join. 3. Verify replication between domain controllers using the following PowerShell commands:
Check Domain Controllers
Get-ADDomainController -Filter *
Check Replication Status
repadmin /replsummary
Check Forest and Domain Information
Get-ADDomain Get-ADForest
Summary: This guide describes how to configure an Additional Domain Controller (ADC) in an existing forest. An ADC ensures redundancy, improves reliability, and supports load balancing for Active Directory services.
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