WGU D386 Exam | Hardware and Operating Systems Essentials | 124 Comprehensive Study Guide Questions with Correct Answers and Rationale | New Update 2026/27 | Graded A

WGU D386 Exam | Hardware and Operating Systems Essentials
| 124 Comprehensive Study Guide Questions with Correct
Answers and Rationale | New Update 2026/27 | Graded A




Question 1
System software that acts as a "go-between", allowing computer hardware and other
software to communicate with each other is called:
A. Application software
B. Operating system
C. Utility software
D. Firmware
Correct Answer: B. Operating system
Rationale: An operating system (OS) is system software that acts as an intermediary between
computer hardware and software applications, allowing them to communicate effectively. It
manages hardware resources, provides services to applications, and creates a user interface.
Application software (A) runs on top of the OS. Utility software (C) performs specific
maintenance tasks. Firmware (D) is stored on ROM chips.


Question 2
What is the purpose of a computer operating system?
A. To store user files
B. To function as a resource manager
C. To create documents
D. To connect to the internet
Correct Answer: B. To function as a resource manager
Rationale: The primary purpose of an operating system is to function as a resource manager,
allocating and managing computer resources such as CPU time, memory, storage, and I/O
devices among users and applications. While an OS does facilitate file storage (A), document
creation (C), and internet connectivity (D), resource management is its fundamental purpose.

,Question 3
What kind of software are the Mac OS X and Windows 10 programs?
A. Application software
B. Operating system (OS)
C. Utility software
D. Firmware
Correct Answer: B. Operating system (OS)
Rationale: Mac OS X and Windows 10 are operating systems—system software that manages
hardware resources, provides a user interface, and runs application programs. They are the
foundational software on which other applications run. They are not application software (A),
utility software (C), or firmware (D).


Question 4
What operating system is open-sourced and allows its source code to be modified and
redistributed?
A. Windows
B. macOS
C. Android
D. iOS
Correct Answer: C. Android
Rationale: Android is open-source (based on the Linux kernel), allowing developers to modify
and redistribute its source code. Windows (A) and macOS (B) are proprietary, and iOS (D) is
closed-source (though some components are open). This openness is a key feature of Android.


Question 5
What primarily manages the operating of one or more virtual machines within a virtualized
environment?
A. Host OS
B. Hypervisor
C. Guest OS
D. Virtual switch
Correct Answer: B. Hypervisor

,Rationale: A hypervisor (also called a virtual machine monitor) is the software that creates,
runs, and manages virtual machine instances on a physical host. The host OS (A) runs on the
physical machine. Guest OS (C) runs inside the VM. Virtual switches (D) handle network traffic
between VMs.


Question 6
What is a feature of cloud-based operating systems?
A. They require local storage
B. They are primarily stateless
C. They are only used in private clouds
D. They cannot be virtualized
Correct Answer: B. They are primarily stateless
Rationale: Cloud-based operating systems are designed to be stateless—they do not maintain
persistent state between sessions. This allows them to be easily deployed, scaled, and replaced
without data loss (data is stored in separate storage services). This is a key feature for cloud
environments.


Question 7
A unique set of services provided by operating systems for use by applications that have to be
accounted for by different operating systems is called:
A. APIs
B. System calls
C. Drivers
D. Libraries
Correct Answer: B. System calls
Rationale: System calls are the unique set of services provided by operating systems for use by
applications. Each OS has its own set of system calls, which is why applications designed for one
OS typically do not work on another without modification. APIs (A) provide a consistent
interface, drivers (C) communicate with hardware, and libraries (D) contain reusable code.


Question 8
A set of software routines that allows one software system to work with another is called:

, A. System calls
B. Application Programming Interface (API)
C. Drivers
D. Firmware
Correct Answer: B. Application Programming Interface (API)
Rationale: An Application Programming Interface (API) is a set of software routines that allows
one software system to work with another. APIs provide a standard way for applications to
interact with operating systems, libraries, and other services. System calls (A) are specific OS
functions. Drivers (C) communicate with hardware. Firmware (D) is stored on ROM.


Question 9
Why do applications designed to work on one operating system not work on a different
operating system?
A. Different hardware requirements
B. Unique system calls
C. Different file formats
D. Different user interfaces
Correct Answer: B. Unique system calls
Rationale: Each operating system has its own unique set of system calls that applications use to
interact with the OS. Applications compiled for one OS make system calls specific to that OS,
which are not available on other OSs. This is the primary reason applications are not cross-
platform without modification or emulation.


Question 10
Multitasking systems found in laptops and workstations are called:
A. Single-user systems
B. Multi-user systems
C. Real-time systems
D. Embedded systems
Correct Answer: A. Single-user systems
Rationale: Single-user systems are multitasking systems found in laptops and workstations
designed for use by one person at a time. Multi-user systems (B) support multiple concurrent