220-1102 Operating Systems Practice Question

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✗

  bootrec /fixmbr

  Why it's wrong here

  The `bootrec /fixmbr` command rewrites the master boot record (MBR) on the first disk sector, which is responsible for locating the active partition and loading that partition's boot sector. However, the "Bootmgr is missing" error typically arises after the MBR has already transferred control, meaning the partition boot sector (PBR) or the Boot Configuration Data (BCD) is damaged or missing. On modern UEFI/GPT systems, the MBR isn't even used for booting, so rewriting it cannot repair the boot sector that directly loads Bootmgr.

• ✓

  bootrec /fixboot

  Why this is correct

  The `bootrec /fixboot` command writes a new partition boot sector (PBS) to the system partition, which contains the initial code that looks for and launches `bootmgr`. When that boot sector is corrupted, overwritten by a non-Windows boot loader, or formatted with an incompatible filesystem signature, Windows displays "Bootmgr is missing" before the BCD is ever read. Repairing the PBS restores the correct chain of execution from firmware → boot sector → Bootmgr, making this the most direct and appropriate fix for the specific boot-sector failure indicated by this error.

• ✗

  bootrec /rebuildbcd

  Why it's wrong here

  `bootrec /rebuildbcd` is incorrect because it scans for Windows installations and rebuilds the Boot Configuration Data (BCD) store, which Bootmgr reads to locate the operating system. The "Bootmgr is missing" error signifies an issue with the boot sector or Master Boot Record (MBR) preventing Bootmgr from loading initially, not a corrupted BCD. This command is tempting as it is a common boot repair utility, and would be the correct choice if the BCD store itself was damaged, preventing Windows from being found after Bootmgr has successfully loaded.

• ✗

  bootrec /scanos

  Why it's wrong here

  The `bootrec /scanos` command scans all disks for Windows installations and lists the results, but it performs no writes or repairs to any boot component. The "Bootmgr is missing" error occurs in the earliest stage of the boot process, before the BCD store or even Bootmgr itself is loaded, so simply discovering that an OS exists on disk cannot fix the missing or unreadable boot manager. It is a diagnostic step that would be useful only after a successful boot repair to confirm the OS partition is recognized, not a remedy for a corrupted boot sector.

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