What is MMC?
MMC is a shell for administrative tools. On its own it does almost nothing; the tools it hosts are snap-ins. A saved console, with one or more snap-ins loaded, is a file with the .msc extension. When you run devmgmt.msc, Windows opens mmc.exe with the Device Manager snap-in loaded.
Because every snap-in uses the same layout, with a console tree on the left, a details pane in the middle and an Actions pane on the right, knowing one MMC tool makes the others feel familiar. Snap-ins can also be combined: Computer Management is simply a prebuilt console that holds several of them in one tree.
Common snap-ins and their commands
| Tool | Command | Used for |
|---|---|---|
| Event Viewer | eventvwr.msc | System, Application and Security logs |
| Disk Management | diskmgmt.msc | Initializing disks, partitions, volumes and drive letters |
| Device Manager | devmgmt.msc | Drivers and hardware status |
| Services | services.msc | Starting and stopping services and setting their startup type |
| Task Scheduler | taskschd.msc | Scheduled tasks and their triggers |
| Local Users and Groups | lusrmgr.msc | Local accounts and group membership |
| Certificate Manager | certmgr.msc | The current user's certificates |
| Performance Monitor | perfmon.msc | Performance counters, logs and reports |
| Local Group Policy Editor | gpedit.msc | Local computer and user policy settings |
| Computer Management | compmgmt.msc | One console that bundles several of the snap-ins above |
Local Users and Groups and the Local Group Policy Editor are not included in Windows Home editions.
Building a custom console
- Run
mmcto open an empty console. - Choose File > Add/Remove Snap-in (
Ctrl+M). - Pick the snap-ins you need. Some ask what to manage: the Certificates snap-in asks for My user account, Service account or Computer account, and many snap-ins can target the local computer or another computer on the network.
- Save the console as an
.mscfile to reuse it.
A console saved in author mode can be changed freely; one saved in a user mode limits what the next person can change. That lets an administrator give a help desk team a console with only the tools they need. Many snap-ins need administrator rights, so expect a UAC prompt or use Run as administrator.
What is not an MMC snap-in
Several familiar tools are standalone programs, not snap-ins: Task Manager (taskmgr), Registry Editor (regedit), System Configuration (msconfig), System Information (msinfo32) and Resource Monitor (resmon). A command ending in .msc is the giveaway for MMC. MMC also has nothing to do with eMMC, the embedded flash storage used in low-cost laptops and phones.
MMC on the CompTIA A+ exam
MMC snap-ins are Core 2 Windows tools material, and questions often describe a task and ask for the right tool or command. Cues:
- Find out why a service failed at startup:
eventvwr.msc, thenservices.msc. - A new drive doesn't appear in File Explorer:
diskmgmt.mscto initialize, partition and format it. - A device shows a yellow exclamation mark:
devmgmt.msc. - Import or inspect a user certificate:
certmgr.msc. gpedit.mscorlusrmgr.mscwon't open: the PC is probably running a Home edition.- Any
.mscfile is an MMC console.