What command should a technician run to check and repair a corrupted Master Boot Record (MBR)?

To check and repair a corrupted Master Boot Record (MBR), the most appropriate command to use is "bootrec." This command is part of the Windows Recovery Environment and is specifically designed to troubleshoot and repair issues related to the boot process, including the MBR.

When a technician runs the bootrec command, they can utilize various options within it, such as "bootrec /fixmbr," which explicitly repairs the MBR while preserving the existing partitioning. This can resolve issues where the system is unable to boot due to corruption in the MBR, allowing the operating system to load correctly. The command is useful not only for fixing the MBR but also for other boot configuration problems, making it a versatile tool in recovery scenarios.

The other options, while related to boot management, do not serve the specific purpose of repairing a corrupted MBR. For instance, "bootfix" and "fixmbr" suggest similar functionalities but are not standard commands in Windows environments. "mbrcheck" is a tool designed to examine the MBR but does not function to repair it. Thus, in the context of repairing the MBR, "bootrec" stands out as the correct and effective choice.