220-1102 Operating Systems Practice Question
A technician upgrades a Windows 10 Professional workstation from legacy BIOS to UEFI mode. The technician converts the system disk from MBR to GPT using MBR2GPT.exe. After the conversion, the system displays 'Boot configuration data is missing. File: \EFI\Microsoft\Boot\BCD. Error code: 0x000000f'. The technician boots from a Windows 10 installation USB and opens a command prompt. Which command should the technician use to rebuild the BCD for the UEFI environment?
⚠ Common exam trap
Candidates often choose bootrec /rebuildbcd (Option B) because it sounds like the standard way to fix BCD issues, but they overlook that after an MBR-to-GPT conversion, the ESP is empty and requires bcdboot to initialize it properly for UEFI.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
bcdboot C:\Windows /s S:
After converting a system disk from MBR to GPT and switching to UEFI mode, the BCD must be rebuilt in the EFI System Partition (ESP). The bcdboot command copies boot files from the Windows folder to the ESP and creates a new BCD store. Specifying /s S: targets the ESP (typically mounted as S: in the recovery environment), ensuring the boot configuration is correctly placed for UEFI firmware to find it.
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
bootrec /fixmbr rewrites the legacy Master Boot Record, but this workstation boots via UEFI, which uses the GPT partitioning scheme and the EFI System Partition (ESP) instead. Since the MBR isn't involved in the UEFI boot path, this command cannot restore missing boot files or recreate the BCD store, leaving the system unbootable.
- ✗
bootrec /rebuildbcd
Why it's wrong here
bootrec /rebuildbcd scans all drives for Windows installations and attempts to rebuild the BCD store, but it is designed for legacy BIOS boot and may not correctly target the EFI System Partition on a UEFI system. Even if it finds Windows, it often fails to create the necessary UEFI firmware boot entry on the correct ESP, so the workstation still won't start properly.
- ✓
bcdboot C:\Windows /s S:
Why this is correct
bcdboot C:\Windows /s S: is the correct repair because it explicitly copies the boot manager, boot loader, and Windows Boot Configuration Data (BCD) store from the C:\Windows directory to the EFI System Partition designated as S:, then creates a new BCD store that the UEFI firmware can use to launch Windows. This directly rebuilds the entire UEFI boot environment, including the required \EFI\Microsoft\Boot folder structure, making it reliable when the original BCD is missing or corrupt.
- ✗
bcdedit /store C:\boot\bcd
Why it's wrong here
bcdedit /store C:\boot\bcd only modifies an existing BCD store at that specific path; it cannot create a store if it's missing, and on a UEFI system the active BCD store is located on the EFI System Partition (often under \EFI\Microsoft\Boot\BCD), not at C:\boot\bcd. Running this command against the wrong or nonexistent store does nothing to repair the boot configuration, so it's ineffective in this scenario.
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Key term
ESP
ESP (Encapsulating Security Payload) is a core protocol in IPsec that provides confidentiality, data integrity, and authentication for VPN traffic by encrypting and optionally authenticating the payload of IP packets.
Key term
ESP
ESP (Encapsulating Security Payload) provides confidentiality, data origin authentication, connectionless integrity, and anti-replay protection for IP packets.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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