Supporting server roles

Windows Server 2012 includes predefined combinations of services called roles that implement common server functions. Computers running the Windows Server 2012 operating system can perform a wide variety of tasks, using both the software included with the product and third-party applications. The activities Windows Server 2012 performs for network
are known as roles. After you install the Windows Server 2012 operating system, you can use Server Manager or Windows PowerShell to assign one or more roles to that computer.
Some of the Windows Server 2012 editions include all of these roles, whereas others include only some of them. Selecting the appropriate edition of Windows Server has always been a matter of anticipating the roles that the computer must perform. At one time, this was a relatively simple process. You planned your server deployments by deciding which ones would be domain controllers, which ones would be web servers, and so forth. Once you made these decisions, you were done, because server roles were largely static.
With the increased focus on virtualization in Windows Server 2012, however, more administrators will be forced to consider not only what roles a server must perform at the time of the deployment, but what roles they will perform in the future as well.
Using virtualized servers, you can modify your network’s server strategy at will, to accommodate changing workloads and business requirements, or to adapt to unforeseen circumstances. Therefore, the process of anticipating the roles a server will perform must account for the potential expansion of your business, as well as possible emergency needs.