How to Promote a Server to a Domain Controller

Promoting a server to a domain controller (DC) is a critical task for setting up and managing an Active Directory (AD) environment. This process ensures that the server can manage user authentication, group policies, and other network services. Below is a step-by-step guide for promoting a server to a domain controller in a Windows Server environment.

Prerequisites

Before you begin, ensure the following requirements are met:

1. Operating System: Ensure the server is running a supported version of Windows Server (e.g., Windows Server 2019 or 2022).
2. Administrative Privileges: You must have administrative access to the server.
3. Network Configuration: The server must have a static IP address and be connected to the network.
4. DNS Configuration: Ensure that the DNS settings point to an existing domain controller or a DNS server.
5. Forest and Domain Requirements: If adding to an existing domain, ensure the forest and domain functional levels are compatible.

Step 1: Install the Active Directory Domain Services (AD DS) Role

1. Open Server Manager:
   • Click the Start button and select Server Manager.
2. Add Roles and Features:
   • In Server Manager, click Manage > Add Roles and Features.
3. Select Installation Type:
   • Choose Role-based or feature-based installation and click Next.
4. Select Destination Server:
   • Choose the server you want to promote and click Next.
5. Select Server Roles:
   • Check the Active Directory Domain Services role.
   • A prompt will appear to add additional features. Click Add Features and then click Next.
6. Install the Role:
   • Click Install and wait for the process to complete. No reboot is required at this stage.

Step 2: Promote the Server to a Domain Controller

1. Post-Deployment Configuration:
   • Once the AD DS role installation is complete, click the Promote this server to a domain controller link in the notification area of Server Manager.
2. Deployment Configuration:
   • Choose the appropriate option based on your environment:
     • Add a domain controller to an existing domain: Use this for adding a DC to an existing domain.
     • Add a new domain to an existing forest: Use this to create a new domain in an existing forest.
     • Add a new forest: Use this to create a new AD forest. Enter the root domain name (e.g., example.com) if creating a new forest.
3. Domain Controller Options:
   • Specify:
     • Domain Name System (DNS) server: Check this box if this server will also host DNS.
     • Global Catalog (GC): Enable if this server will act as a global catalog.
     • Read-only domain controller (RODC): Leave unchecked unless you specifically need an RODC.
   • Set the Directory Services Restore Mode (DSRM) password and confirm it.
4. DNS Options:
   • If DNS is being configured, you may see a warning about delegation. Click Next to proceed.
5. Additional Options:
   • For a new forest, specify the NetBIOS name of the domain (e.g., EXAMPLE).
6. Paths:
   • Specify the paths for the database, log files, and SYSVOL folder, or leave the defaults.
7. Review and Validate:
   • Review the configuration options and click Next. The wizard will validate the settings.
8. Install:
   • Click Install to begin the promotion process. The server will automatically reboot upon completion.

Step 3: Verify the Promotion

After the server restarts:

1. Log In:

   • Use a domain administrator account to log in.

2. Check Active Directory:

   • Open Active Directory Users and Computers (ADUC) to ensure the domain controller is listed.

3. Check DNS:

   • Open the DNS Manager to confirm that DNS records for the domain and server have been created.

4. Run Diagnostic Tests:

   • Use tools like dcdiag to verify the health of the domain controller:

     dcdiag /v
     

5. Replicate Changes (for additional DCs):

   • Use repadmin to check and force replication if needed:

     repadmin /replsummary
     

Troubleshooting

• DNS Issues: Verify that the DNS settings are correct and point to an existing DC or DNS server.
• Replication Issues: Use repadmin to identify and resolve replication problems.
• Firewall Rules: Ensure necessary ports (e.g., 135, 389, 445) are open for AD communication.

Conclusion

Promoting a server to a domain controller is a straightforward but critical process in building a robust Active Directory infrastructure. By following these steps, you can ensure a smooth and secure setup for your network environment. Regular monitoring and maintenance will help ensure the stability and reliability of your domain controllers.