Domain controllers are servers configured to run Active Directory. They serve as the central repository for network information that facilitates services like file and printer sharing, authentication, group policy enforcement and more. You can set up an Active Directory site using Windows Server 2008 by first installing all necessary roles for running it successfully – domain controller roles being one such.
Use Server Manager, click Roles link on the left, and add roles from there. When the Role-Based or Feature-Based Installation wizard opens, read through its information (if you choose), and click Next before selecting Active Directory Domain Services to install them.
After choosing to deploy the Active Directory Domain Services role, it is necessary to select both a Global Catalog server and Read-only Domain Controllers (RODC). Furthermore, when placing files related to AD on servers – including its database, log files, and SYSVOL – on separate or the same servers; for optimal performance it is advised that logs be located separately than database. Lastly, specify a password for Directory Services Restore Mode administrator accounts which allows accessing server for troubleshooting and disaster recovery purposes.
On the next screen, you will be asked to set an AD site name. This name serves to distinguish sites within your organization; either use the default site name DSSiteName or create your own by clicking New. After setting your site name and specifying where SYSVOL folder resides on domain controller server(s), depending on your environment you can either choose to put it directly onto server(s), mirrored disk(s) or have it coexist on two servers simultaneously if primary server becomes unavailable (if using two server’s instead). If using mirror disk then second server will become alternate in case primary server becomes unavailable (alternate server will act as alternate when primary server becomes unavailable).
Once you have completed site configuration, you can move on to installing any additional roles required for deployment. When finished, your server will prompt you to reboot before Active Directory Users and Computers is opened for verification that your new domain controller is functioning as desired.
Active Directory site structures provide greater control of replication traffic than is available with traditional Windows NT 4.0 domains, enabling you to ensure logon traffic doesn’t cross WAN links to remote DCs – this feature is known as Microsoft Dfs site-aware and provides significant advantages over random queries on NT 4.0 that would return a list of DCs back to clients.
Another benefit of site structures is creating site link bridges to enable domain controllers in different sites to communicate more easily, which in turn reduces replication traffic sent over slow WAN links.