First of all we should discuss about what is MMC ( Microsoft Management Control ). The primary administrative tool for managing Windows Server 2003 is the MMC. The MMC provides a standardized, common interface for one or more of the applications, called snap-ins, that you use to configure the elements of your environment. These snap-ins are individualized to specific tasks, and can be ordered and grouped within the MMC to your administrative preference.

The primary administrative tools in Windows Server 2003 are MMC consoles with collections of snap-ins suited to a specific purpose. The Active Directory Users and Computers administrative tool, for example, is specifically designed to administer the security principals (Users, Groups, and Computers) in a domain. The snap-ins within the MMC—not the MMC itself—are the administrative tools that you use.

Each MMC contains a collection of one or more tools called snap-ins. A snap-in extends the MMC by adding specific management capability and functionality. There are two types of snap-ins: stand-alone and extension. You can combine one or more snap-ins or parts of snap ins to create customized MMCs, which can then be used to centralize and combine administrative tasks. Although you can use many of the preconfigured consoles for administrative tasks, customized consoles allow for individualization to your needs and standardization within your environment.

Important Tip By creating a custom MMC, you do not have to switch between different programs or individual consoles.

Stand-Alone Snap-Ins:- are provided by the developer of an application. All Administrative Tools for Windows Server 2003, for example, are either single snap-in consoles or preconfigured combinations of snap-ins useful to a particular category of tasks. The Computer Management snap-in, for example, is a collection of individual snap-ins useful to a unit.

Extension Snap-Ins: - or extensions, are designed to work with one or more stand-alone snap-ins, based on the functionality of the stand-alone. When you add an extension, Windows Server 2003 places the extension into the appropriate location within the stand-alone snap-in.Many snap-ins offer stand-alone functionality and extends the functionality of other snap-ins. For example, the Event Viewer snap-in reads the event logs of computers. If the Computer Management object exists in the console, Event Viewer automatically extends each instance of a Computer Management object and provides the event logs for the computer. Alternatively, the Event Viewer can also operate in stand-alone mode, in which case it does not appear as a node below the Computer Management node.