CompTIA A+ Core 2 (220-1202)Software TroubleshootingMedium

A technician is troubleshooting a Windows 10 desktop that fails to boot, displaying the error 'Operating System not found'. The technician confirms that the hard drive is detected in the BIOS/UEFI. Which bootrec option should the technician use to attempt to repair the Master Boot Record (MBR)?

  1. Abootrec /rebuildbcd
  2. Bbootrec /scanos
  3. Cbootrec /fixmbr
  4. Dbootrec /fixboot
Show answer & explanation

Correct answer: C. bootrec /fixmbr

The 'Operating System not found' error, with the hard drive detected, strongly suggests an issue with the Master Boot Record (MBR). The 'bootrec /fixmbr' command is specifically designed to write a new MBR to the system partition, resolving MBR corruption issues.

Why the other options are wrong

  • A. bootrec /rebuildbcd rebuilds the Boot Configuration Data (BCD) store, which is used when the BCD is corrupt or missing, but not specifically for MBR issues causing 'OS not found'.
  • B. bootrec /scanos scans for Windows installations and adds them to the BCD, not for repairing the MBR.
  • D. bootrec /fixboot writes a new boot sector to the system partition, which is different from the MBR.

Repairing MBR/Boot Sector

The 'bootrec' command-line utility, used from the Windows Recovery Environment (WinRE), helps resolve boot issues by repairing critical boot components like the Master Boot Record (MBR) and boot sector.

  • bootrec /fixmbr writes a new MBR.
  • bootrec /fixboot writes a new boot sector.
  • bootrec /rebuildbcd rebuilds the Boot Configuration Data store.
  • Accessed via Advanced Startup Options (WinRE).

Memory trick: Boot's broken? Hit the 'rec' button, fix it quick!

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