Install DHCP Server role
The following command from the command prompt should add the DHCP Server Role.
C:\Users\Administrator>start /w ocsetup DHCPServer
In Windows Server 2008 Core, the Role name is “DHCPServerCore”. So, in Windows Server 2008 Core installation, it is
C:\Users\Administrator>start /w ocsetup DHCPServerCore
Set DHCP Service to be Automatic
By default, after the role is enabled, the Service is still disabled. Hence Set the type to Auto as follows
C:\Users\Administrator> sc config dhcpserver start= auto
Start the DHCP Server
C:\Users\Administrator>net start dhcpserver
http://www.windowsreference.com/windows-server-2008/how-to-add-a-dhcp-server-from-command-line-in-windows-server-2008/