WGU D386 Hardware and Operating Systems Essentials Object
Assessment (OA) Exam Study Guide | Complete Exam Questions
with Answers and Detailed Rationales 100% Verified Correct
Solutions | 2026/2027 Latest Update
Question 1
Which CPU component controls and coordinates the execution of
instructions?
A. ALU
B. Control Unit
C. Hard disk
D. RAM
Correct Answer: B. Control Unit
Rationale: The Control Unit directs CPU operations by interpreting
instructions and coordinating the activities required to execute them. The ALU
performs arithmetic and logical operations, while RAM and storage provide
locations for data and instructions rather than directly coordinating CPU
execution.
Question 2
Which RAID level combines disk striping with disk mirroring?
A. RAID 0
B. RAID 1
C. RAID 5
D. RAID 10
Correct Answer: D. RAID 10
Rationale: RAID 10 combines the concepts of RAID 1 mirroring and RAID 0
striping. This provides redundancy through mirroring while also distributing
data across drives for performance. RAID 10 therefore requires multiple
drives and combines characteristics of the two RAID approaches.
pg. 1
,Question 3
Which type of memory is volatile and normally loses its contents when
electrical power is removed?
A. ROM
B. RAM
C. SSD
D. Flash memory
Correct Answer: B. RAM
Rationale: Random Access Memory (RAM) is volatile memory, meaning its
stored information depends on continuous electrical power. It temporarily
holds programs and data that the CPU is actively using. ROM, SSDs, and flash
memory are nonvolatile, so their contents remain stored after power is
removed.
Question 4
A computer frequently accesses the same instructions and data repeatedly.
Which hardware component can reduce the time required for the CPU to
access this frequently used information?
A. Cache
B. Optical drive
C. Power supply
D. Expansion slot
Correct Answer: A. Cache
Rationale: CPU cache is high-speed memory designed to store frequently
accessed instructions and data close to the processor. By reducing the need to
repeatedly access slower main memory, cache can improve processing
performance. Cache is generally much smaller but faster than RAM.
Question 5
pg. 2
,Which CPU component is primarily responsible for performing arithmetic and
logical operations?
A. Control Unit
B. Arithmetic Logic Unit (ALU)
C. Register
D. Cache
Correct Answer: B. Arithmetic Logic Unit (ALU)
Rationale: The ALU performs arithmetic operations such as addition and
subtraction and logical operations such as AND, OR, and comparisons. The
Control Unit coordinates instruction execution, registers provide very fast
temporary storage, and cache stores frequently accessed instructions and
data.
Question 6
Which storage technology has no moving mechanical parts and generally
provides faster access than a traditional hard disk drive?
A. HDD
B. SSD
C. Magnetic tape
D. Optical disc
Correct Answer: B. SSD
Rationale: A solid-state drive (SSD) uses flash-based storage and has no
spinning platters or mechanical read/write heads. This allows SSDs to provide
fast access times and generally better resistance to physical shock than
traditional HDDs.
Question 7
What is the primary purpose of an operating system?
pg. 3
, A. To replace the CPU
B. To manage hardware and software resources
C. To permanently store all user files
D. To increase the physical capacity of RAM
Correct Answer: B. To manage hardware and software resources
Rationale: An operating system acts as an intermediary between applications,
users, and computer hardware. It manages resources such as CPU time,
memory, storage, files, devices, and processes. It does not replace physical
hardware or permanently store every user file.
Question 8
Which operating-system function determines which process receives CPU
time?
A. Process management
B. File compression
C. Disk formatting
D. Device manufacturing
Correct Answer: A. Process management
Rationale: Process management includes controlling processes and
determining when they run. The operating system uses scheduling
mechanisms to allocate CPU time among processes. File compression, disk
formatting, and hardware manufacturing are not primary process-
management functions.
Question 9
A computer has insufficient physical RAM, but the operating system uses part
of its storage device to temporarily hold memory data. What concept does this
describe?
pg. 4
Assessment (OA) Exam Study Guide | Complete Exam Questions
with Answers and Detailed Rationales 100% Verified Correct
Solutions | 2026/2027 Latest Update
Question 1
Which CPU component controls and coordinates the execution of
instructions?
A. ALU
B. Control Unit
C. Hard disk
D. RAM
Correct Answer: B. Control Unit
Rationale: The Control Unit directs CPU operations by interpreting
instructions and coordinating the activities required to execute them. The ALU
performs arithmetic and logical operations, while RAM and storage provide
locations for data and instructions rather than directly coordinating CPU
execution.
Question 2
Which RAID level combines disk striping with disk mirroring?
A. RAID 0
B. RAID 1
C. RAID 5
D. RAID 10
Correct Answer: D. RAID 10
Rationale: RAID 10 combines the concepts of RAID 1 mirroring and RAID 0
striping. This provides redundancy through mirroring while also distributing
data across drives for performance. RAID 10 therefore requires multiple
drives and combines characteristics of the two RAID approaches.
pg. 1
,Question 3
Which type of memory is volatile and normally loses its contents when
electrical power is removed?
A. ROM
B. RAM
C. SSD
D. Flash memory
Correct Answer: B. RAM
Rationale: Random Access Memory (RAM) is volatile memory, meaning its
stored information depends on continuous electrical power. It temporarily
holds programs and data that the CPU is actively using. ROM, SSDs, and flash
memory are nonvolatile, so their contents remain stored after power is
removed.
Question 4
A computer frequently accesses the same instructions and data repeatedly.
Which hardware component can reduce the time required for the CPU to
access this frequently used information?
A. Cache
B. Optical drive
C. Power supply
D. Expansion slot
Correct Answer: A. Cache
Rationale: CPU cache is high-speed memory designed to store frequently
accessed instructions and data close to the processor. By reducing the need to
repeatedly access slower main memory, cache can improve processing
performance. Cache is generally much smaller but faster than RAM.
Question 5
pg. 2
,Which CPU component is primarily responsible for performing arithmetic and
logical operations?
A. Control Unit
B. Arithmetic Logic Unit (ALU)
C. Register
D. Cache
Correct Answer: B. Arithmetic Logic Unit (ALU)
Rationale: The ALU performs arithmetic operations such as addition and
subtraction and logical operations such as AND, OR, and comparisons. The
Control Unit coordinates instruction execution, registers provide very fast
temporary storage, and cache stores frequently accessed instructions and
data.
Question 6
Which storage technology has no moving mechanical parts and generally
provides faster access than a traditional hard disk drive?
A. HDD
B. SSD
C. Magnetic tape
D. Optical disc
Correct Answer: B. SSD
Rationale: A solid-state drive (SSD) uses flash-based storage and has no
spinning platters or mechanical read/write heads. This allows SSDs to provide
fast access times and generally better resistance to physical shock than
traditional HDDs.
Question 7
What is the primary purpose of an operating system?
pg. 3
, A. To replace the CPU
B. To manage hardware and software resources
C. To permanently store all user files
D. To increase the physical capacity of RAM
Correct Answer: B. To manage hardware and software resources
Rationale: An operating system acts as an intermediary between applications,
users, and computer hardware. It manages resources such as CPU time,
memory, storage, files, devices, and processes. It does not replace physical
hardware or permanently store every user file.
Question 8
Which operating-system function determines which process receives CPU
time?
A. Process management
B. File compression
C. Disk formatting
D. Device manufacturing
Correct Answer: A. Process management
Rationale: Process management includes controlling processes and
determining when they run. The operating system uses scheduling
mechanisms to allocate CPU time among processes. File compression, disk
formatting, and hardware manufacturing are not primary process-
management functions.
Question 9
A computer has insufficient physical RAM, but the operating system uses part
of its storage device to temporarily hold memory data. What concept does this
describe?
pg. 4
