What does POST do?

• A. Loads the operating system kernel into memory.
• B. Performs memory parity checks.
• C. Initializes peripheral devices at boot.
• D. Power-On Self Test validates essential hardware before handing off to the bootloader.

Answer: (D)

Power-On Self Test runs at startup to verify essential hardware before the system hands control to the boot process. The firmware (BIOS/UEFI) quickly checks that core components—CPU, memory, motherboard/chipset, power supply, and basic I/O controllers—are present and functioning. If POST detects a problem, it reports an error (via screen messages or beeps) and may halt, preventing the boot from continuing. Only after POST completes successfully does the firmware proceed to load the bootloader, which then loads the operating system kernel. While POST may perform a memory check, its main role is validating that critical hardware is okay, not loading the OS or performing detailed memory parity checks.