WGU D386 PA | Questions and Correct Answers with Rationale | New Update 2026/27 | Graded A+

WGU D386 PA | Questions and Correct Answers with
Rationale | New Update 2026/27 | Graded A+


Question 1
What is used by the operating system to hold its system code and other
programs?
A. Hard drive
B. Random access memory (RAM)
C. ROM
D. Cache memory
Correct Answer: B. Random access memory (RAM)
Rationale: RAM (Random Access Memory) is used by the operating system to hold
its system code and other programs that are currently running. RAM is volatile—
data is lost when power is turned off. The OS is loaded from the hard drive into
RAM during boot, and active programs and data are stored in RAM for fast access
by the CPU. The hard drive (A) is for permanent storage. ROM (C) is read-only
memory used for firmware. Cache memory (D) is a small, fast memory used to
speed up data access.


Question 2
What is an example of a server operating system?
A. Windows 10
B. Red Hat Enterprise Linux
C. macOS
D. iOS
Correct Answer: B. Red Hat Enterprise Linux
Rationale: Red Hat Enterprise Linux (RHEL) is a server operating system designed
for enterprise servers, data centers, and cloud environments. It provides features

,like high availability, security, and scalability for server workloads. Windows 10 (A)
and macOS (C) are desktop operating systems, while iOS (D) is a mobile operating
system.


Question 3
What is a fundamental building block of an operating system that keeps track of
each process in memory, including whether to run it or wait for some event?
A. File system management
B. Process control management
C. Memory management
D. I/O management
Correct Answer: B. Process control management
Rationale: Process control management (also called process scheduling or task
management) is a fundamental function of an operating system that tracks each
process's state, priority, resource allocation, and scheduling. It determines which
process runs at any given time and manages transitions between states (ready,
running, waiting, terminated). File system management (A) handles data storage
and retrieval. Memory management (C) deals with RAM allocation. I/O
management (D) handles input/output operations.


Question 4
What is an example of a system call used by the POSIX API for POSIX-based
systems running UNIX, Linux, and macOS?
A. Write()
B. Read()
C. Open()
D. Close()
Correct Answer: B. Read()
Rationale: The read() system call is a fundamental POSIX function used to read
data from a file descriptor. It is part of the standard POSIX API and is used across

, UNIX, Linux, and macOS systems. While write(), open(), and close() are also POSIX
system calls, read() is the example provided in the source material.


Question 5
Which part of a hard disk drive is responsible for storing actual data?
A. Read/write heads
B. Platters
C. Spindle
D. Actuator arm
Correct Answer: B. Platters
Rationale: Platters are the circular, rigid disks inside a hard drive that store data
magnetically. Data is written to and read from the platters by read/write heads
(A). The spindle (C) rotates the platters. The actuator arm (D) positions the
read/write heads over the correct location on the platters.


Question 6
How do computers avoid burdening the main central processing unit (CPU) with
programmed I/O (PIO)?
A. By using a faster CPU
B. By offloading to a direct-memory-access (DMA) controller
C. By using more RAM
D. By increasing the clock speed
Correct Answer: B. By offloading to a direct-memory-access (DMA) controller
Rationale: DMA (Direct Memory Access) allows hardware subsystems to access
memory independently of the CPU. This offloads I/O operations from the CPU,
allowing the CPU to perform other tasks while data transfers occur. This is more
efficient than Programmed I/O (PIO), where the CPU must execute instructions for
each data transfer.