Dynamic Host Configuration Protocol (DHCP) is the service that automates the networking process. Instead of manually typing in IP addresses for every virtual machine, the DHCP role on Windows Server 2008 allows the server to automatically "lease" IP addresses, subnet masks, and DNS settings to any client that connects to the network. This ensures that every workstation has a unique identity and, crucially, knows exactly where to find the Domain Controller.

You can watch my YouTube video about this using VirtualBox. CORRECTION: For per Section Scoping, watch this video.