What value of the "Boot Record Signature" is used to indicate that the boot-loader exists?

The correct answer is A. AA55. The Master Boot Record (MBR) ends with a 2-byte boot signature of 0x55AA, which in little-endian byte order as stored on disk appears as AA 55. This magic number at bytes 510-511 of the first sector signals to the BIOS that the sector contains a valid bootloader and the system…

Submitted by marco_it· Apr 18, 2026Disk Forensics

Question

Options

AAA55
B00AA
CAA00
DA100

How the community answered

(26 responses)

A
88% (23)
B
8% (2)
D
4% (1)

Explanation

The Master Boot Record (MBR) ends with a 2-byte boot signature of 0x55AA, which in little-endian byte order as stored on disk appears as AA 55. This magic number at bytes 510-511 of the first sector signals to the BIOS that the sector contains a valid bootloader and the system can proceed with booting. If this signature is absent or corrupted, the BIOS will not recognize the sector as bootable. The other values listed (00AA, AA00, A100) are not valid MBR boot signatures.

Topics

#Boot Record Signature#Master Boot Record (MBR)#Boot Sector#Disk Structure

Community Discussion

No community discussion yet for this question.

Full 312-49 Practice