A: The DISM command can be used to add and remove roles and features from the current OS or even an OS image.
This makes it a simple way to add and remove the features required to change the configuration level of Windows Server 2012 (formerly code-named Windows Server 8). Notice the feature names in DISM are different from those in Windows PowerShell.
From full server with GUI to Server Core, use this command:
From Server Core to full server with GUI, use this command: