Windows Server 2008 R2 Server Core

New to Windows Server 2008 and continued support with Windows Server 2008 R2 is a Server Core version of the operating system. Windows Server 2008 R2 Server Core. When a system boots up with Server Core installed on it, the system does not load up the normal Windows graphical user interface. Instead, the Server Core system boots to a logon prompt, and from the logon prompt, the system drops to a DOS command prompt. There is no Start button, no menu—no GUI at all.

Server Core is not sold as a separate edition, but rather as an install option that comes with the Standard, Enterprise, Datacenter, and Web Server Editions of the operating system. So, when you purchase a license of Windows Server 2008 R2, the DVD has both the normal GUI Edition code plus a Windows Server 2008 R2 Server Core version.

The operating system capabilities are limited to the edition of Server Core being installed, so a Windows Server 2008 R2, Enterprise Edition Server Core server has the same memory and processor limits as the regular Enterprise Edition of Windows Server 2008 R2.

Server Core has been a great version of Windows for utility servers such as domain controllers, DHCP servers, DNS servers, IIS web servers, or Windows virtualization servers being that the limited overhead provides more resources to the applications running on the server, and by removing the GUI and associated applications, there’s less of a security attack footprint on the Server Core system. Being that most administrators don’t play Solitaire or use Media Player on a domain controller, those are applications that don’t need to be patched, updated, or maintained on the GUI-less version of Windows. With fewer applications to be patched, the system requires less maintenance and management to keep operational.

Source of Information : Sams - Windows Server 2008 R2 Unleashed