In the Windows operating system, the BOOTREC command plays a crucial role in troubleshooting and fixing boot-related issues. It is an essential tool for system administrators and users who encounter problems such as a corrupted or missing boot manager, invalid or damaged boot configuration data (BCD), or issues with the Master Boot Record (MBR) or Boot Sector. By understanding and utilizing the BOOTREC command, users can effectively resolve these issues and ensure the smooth functioning of their Windows system.

Examples:

1. Rebuilding the BCD:
The BCD contains crucial information about the boot configuration of the system. If it gets corrupted or becomes invalid, the system may fail to boot. To rebuild the BCD using the BOOTREC command, follow these steps:

a. Boot your system using a Windows installation media or recovery disk.
b. Select the language preferences and click "Next."
c. Click on "Repair your computer" and choose the operating system you want to repair.
d. Open the Command Prompt.
e. Type the following command and press Enter:

      bootrec /rebuildbcd

f. Follow the on-screen instructions to complete the process.

2. Fixing the Master Boot Record (MBR):
The MBR is the first sector of the hard drive that contains the boot loader. If it gets damaged or overwritten by another operating system, the system may fail to boot. To fix the MBR using the BOOTREC command, follow these steps:

a. Boot your system using a Windows installation media or recovery disk.
b. Select the language preferences and click "Next."
c. Click on "Repair your computer" and choose the operating system you want to repair.
d. Open the Command Prompt.
e. Type the following command and press Enter:

      bootrec /fixmbr

f. Follow the on-screen instructions to complete the process.