What is a first sector ("sector zero") of a hard disk?

The correct answer is A. Master boot record. The very first sector of a hard disk - Sector 0, also called the 'first sector' or 'sector zero' - is the Master Boot Record (MBR). The MBR contains the bootloader code (the first 446 bytes), the partition table (64 bytes describing up to four primary partitions), and a boot sign

Submitted by emma.c· Apr 18, 2026Disk Forensics

Question

Options

AMaster boot record
BSystem boot record
CSecondary boot record
DHard disk boot record

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(33 responses)

A
91% (30)
B
3% (1)
D
6% (2)

Explanation

The very first sector of a hard disk - Sector 0, also called the 'first sector' or 'sector zero' - is the Master Boot Record (MBR). The MBR contains the bootloader code (the first 446 bytes), the partition table (64 bytes describing up to four primary partitions), and a boot signature (2 bytes, 0x55AA). The BIOS reads the MBR during startup to locate the active partition and hand off control to the operating system's bootloader. It is a critical forensic artifact as it can reveal partition structure and tampering.

Topics

#Hard disk structure#Master Boot Record#Sector zero#Boot process

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