In Windows Server 2008, the setup of a domain controller in an Active Directory network has undergone a couple of notable changes. Let us walk through the setup of a brand new Active Directory infrastructure to illustrate this.
When you execute dcpromo.exe at the command-line, the application will first check for the presence of the Active Directory Domain Services (AD DS) binaries.
AD DS is what we presently still refer to as Active Directory service / database that makes a Windows 2003/2000 machine a domain controller. If this pre-requisite is absent, installation will take place automatically before the familiar dcpromo Wizard interface appears. The AD DS binaries is a Windows server role that can be separately installed in advance from Server Manager.
At the initial Wizard page, tick on the “Use advanced mode installation” checkbox (default is not selected) to walk through the installation if you want to exert more control over the process and the default canned settings are not suitable for your environment. Not only that, some of the options can only be configured in advanced mode, such as the creation of a new domain in an existing forest or adding new DCs to an existing domain. This mode can be directly enabled by passing the /adv switch to dcpromo.