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WGU D686 OPERATING SYSTEMS FOR
COMPUTER SCIENTISTS OA
COMPREHENSIVE STUDY GUIDE 2026 FULL
QUESTIONS AND SOLUTIONS GRADED A+
◍ What is a program counter (PC). Answer: A register that holds the address of the next instruction to execute ◍ Which key decrypts in asymmetric encryption. Answer: Private key ◍ What is a computer system composed of. Answer: Hardware, operating system, application programs, and users ◍ Which type of RAM is commonly installed on motherboards and loses data rapidly, requiring a constant refresh?. Answer: DRAM ◍ What is SSTF disk scheduling. Answer: Shortest Seek Time First - services the request closest to current head position ◍ What is the security device that protects a network from hackers and can also simultaneously prevent computers within the network from accessing undesirable content on the internet?. Answer: Firewall ◍ What is memory swapping. Answer: Moving entire processes between main memory and disk (backing store) ◍ What is an advantage of using a text editor instead of an integrated
development environment (IDE)?. Answer: Fewer distractions
◍ What is an example of a Microsoft-based mobile operating system?. Answer: Surface Duo
◍ Where are files stored in UNIX. Answer: UFS (Unix File System)
◍ Which feature of an IDE provides a list of variables that are already declared in the program as the developer starts typing?. Answer: Autocomplete
◍ Which cloud computing characteristic provides a company with the ability to automatically scale down processing resources as needed?. Answer: Elasticity
◍ Which virtual machine tool involves testing out an application where files are not saved to the drive or memory and never affect the physical machine?. Answer: Virtual sandbox
◍ What is segment offset. Answer: The address within a segment, showing the relative position from the segment's base address
◍ What is the optimal page replacement algorithm. Answer: Replaces the page that will not be used for the longest time in the future
◍ What is page replacement. Answer: The process of choosing which page to remove from memory when a new page needs to be loaded
◍ What is a segment table. Answer: A table that maps segment numbers to their base address and limit in physical memory
◍ Which technique can be used by DNS to battle email spam?.
reconfigure?. Answer: Bus
◍ What is "something you are" authentication. Answer: Biometrics - fingerprint, face recognition, iris scan
◍ Which network device offers the capability of centralizing the control of resources and compartmentalizing files for improved reliability?. Answer: Server
◍ What describes why Type-1 hypervisors are more efficient than Type- hypervisors?. Answer: A Type-1 hypervisor accesses the physical hardware directly.
◍ What is the minimum RAM requirement when installing and configuring a 64-bit Windows 11 system?. Answer: 4 GB
◍ What is the difference between PC and PCB. Answer: PC tracks only the next instruction location; PCB stores the full process state including PC, registers, and scheduling info
◍ What is the difference between a boot virus and rootkit. Answer: Boot virus infects the boot sector/MBR to load before OS; Rootkit hides malware presence and provides hidden admin access
◍ What does maskable interrupt mean. Answer: An interrupt that can be temporarily ignored or disabled by the CPU
◍ What is worst-fit memory allocation. Answer: Allocates the largest available hole
◍ Which is hardware: device driver or device controller. Answer: Device controller is hardware; device driver is software
◍ Why use threads. Answer: Improve responsiveness, enable resource sharing, and allow parallel execution on multicore systems
◍ What is Belady's anomaly. Answer: A phenomenon where increasing the number of page frames can actually increase page faults (occurs with FIFO)
◍ What is best-fit memory allocation. Answer: Allocates the smallest available hole that is large enough for the request
◍ Which set of components make up the central processing unit (CPU)?. Answer: Arithmetic logic unit and control unit
◍ What is disk seek time. Answer: Time for the read/write head to move to the correct track
◍ Which type of twisted pair cable can transmit data at speeds up to 10 Mbps?. Answer: Category 3
◍ What is a characteristic of virtualized containers?. Answer: Containers share the same host operating system.
◍ What is a file system. Answer: Software that manages how files are stored, organized, and accessed on storage devices
◍ What is DMA (Direct Memory Access). Answer: Hardware feature that allows devices to transfer data directly to/from memory without CPU involvement
◍ What is "something you know" authentication. Answer: A password, PIN, or security question
◍ What is polling in I/O. Answer: CPU repeatedly checks if an I/O device is ready - "busy waiting"
◍ Which cache memory is the smallest but fastest?. Answer: L
◍ What is logical memory. Answer: An OS abstraction that programs see - virtual address space that
◍ Which ability describes a security feature in virtualization?. Answer: Isolating the operating system when running multiple concurrent VMs
◍ When is DMA used. Answer: High-speed data transfers like disk I/O to free up the CPU for other tasks
◍ What is a TLB (Translation Lookaside Buffer). Answer: A hardware cache that stores recent logical-to-physical address translations to speed up memory access
◍ What is the bootstrap loader. Answer: Firmware program that finds and loads the OS kernel when the system powers on
◍ What is a mount table. Answer: A table that tracks all currently mounted file systems
◍ Which system hardening technique involves securing a data-based system's ports, data, permissions, and functions?. Answer: Server hardening
◍ What is the function of the operating system?. Answer: It acts as an intermediary between computer users and computer resources.
◍ Which type of network connects devices within the ranges of 30 feet or less?. Answer: Personal area network (PAN)
◍ What is a relative path. Answer: A path specified relative to the current working directory
◍ What is the recommended RAM requirement when creating and editing high-definition media (FHD)?. Answer: 16 GB
◍ What is a shared lock.
Answer: A lock that allows multiple processes to read simultaneously
◍ What is defense in depth. Answer: Security strategy using multiple layers of protection
◍ A client is utilizing servers, data storage, data backup, and software development platforms over an internet connection. Which computing approach is being applied?. Answer: Cloud computing
◍ What is a bus in computer systems. Answer: A communication pathway connecting components (CPU, memory, I/O devices)
◍ Which type of technology would be used to create a wide area network (WAN)?. Answer: Leased lines
◍ What is the file-organization module. Answer: Manages files, logical blocks, and free-space management
◍ What is a temporary holding area for data and programs?. Answer: RAM
◍ What are 4 things a file system must do. Answer: Create files, Read files, Write files, Delete files
◍ Which kind of client-side virtualization is used to create an isolated environment to test an application while ensuring no negative impact on your live system?. Answer: Virtual sandbox
◍ Which type of cloud service makes provisions for hardware infrastructure and operating system software to run client applications?. Answer: Platform as a service (PaaS)
◍ What is NTFS journaling. Answer: A feature that logs changes before making them, enabling recovery after crashes
◍ Which programming language communicates with the back-end stack when considering front-end tech stacks?. Answer: JS
◍ A development team adopts Kafka for streaming purposes. Which protocol should be in place to support this application?. Answer: Transmission Control Protocol (TCP)
◍ Which problem is managed by implementing a file system?. Answer: Logical structure for organizing and storing files on a storage device
◍ What is contiguous allocation. Answer: Storing a file in consecutive disk blocks
◍ What is an example of a system call used by the POSIX API for POSIX-based systems running UNIX, Linux, and macOS?. Answer: Read ()
◍ Which type of DRAM do modern laptops all use?. Answer: SO-DIMM
◍ Why do applications designed to work on one operating system not work on a different operating system?. Answer: Unique system calls
◍ Which type of network attack is worsened by high-speed transfer and the ability to retrieve or upload large amounts of data in a faster way?. Answer: Swarm attack
◍ What is social engineering. Answer: Manipulating people psychologically to gain access or information
◍ What is required to run a hypervisor program on a computer system?. Answer: High-end CPU
◍ Where are files stored in Windows. Answer: NTFS, FAT, or FAT
◍ Which aspect of virtualization manages all physical memory?. Answer: Hypervisor
◍ What is a daisy chain. Answer: A wiring scheme where devices are connected in series, one after another
◍ Which size data path do today's DIMMS use?. Answer: 64-bit
◍ What is memory-mapped I/O. Answer: Accessing I/O devices through memory addresses instead of special I/O ports
◍ Which non-functional requirement (NFR) type deals with restoring a system after a brief system failure?. Answer: Maintainability
◍ What is DDoS. Answer: Distributed Denial of Service - DoS attack from multiple sources simultaneously
◍ What is Dropbox. Answer: A cloud storage service for storing and sharing files
◍ What is session hijacking. Answer: Taking over an active authenticated session between a user and server
◍ Which tool would be appropriate for an organization handling document-based data?. Answer: Mongo Database (MongoDB)
◍ What is the I/O control layer. Answer: Device drivers and interrupt handlers that transfer data between memory and devices
◍ An IT manager is implementing a simple web server for a small-business customer. Which basic tool should the manager implement for this
during business hours?. Answer: Availability
◍ Which kind of software are Mac OS X and Windows 10 programs?. Answer: Operating system (OS)
◍ What is a device controller. Answer: HARDWARE component that interfaces an I/O device with the system
◍ What is a magic number in file systems. Answer: A unique identifier at the start of a file to identify its type
◍ Which page replacement algorithm gives the fewest page faults. Answer: Optimal algorithm (but it's theoretical - requires future knowledge)
◍ Which type of network connects computers and other networking devices in a single large building?. Answer: Local area network (LAN)
◍ Which memory type is stored on a drive and is referred to as a paging file?. Answer: Virtual RAM
◍ What is a tree-structured directory. Answer: A strict hierarchical directory with no sharing - each file has exactly one path
◍ What is the difference between confidentiality and integrity. Answer: Confidentiality prevents unauthorized disclosure; Integrity prevents unauthorized modification
◍ What represents the most common type of tech stack in web applications?. Answer: Fullstack
◍ What is the difference between paging and segmentation. Answer: Paging uses fixed-size units; segmentation uses variable-sized logical units like code, data, stack
◍ There are a number of different types of components of a motherboard.
Which motherboard component is used for support of slower onboard peripherals?. Answer: Southbridge
◍ A project team's requirements often evolve during the development process, and they need to modify the project as it progresses. Why would this team choose to use a tech stack in this scenario?. Answer: Flexibility
◍ What is memory mapping. Answer: Technique to map files or devices into a process's virtual address space
◍ What is a logic bomb. Answer: Malicious code that triggers when a specific condition is met (date, event, etc.)
◍ Which key encrypts in asymmetric encryption. Answer: Public key
◍ After installing a new video editing application, a person notices the application is running slowly. The person restarts the computer and receives an insufficient memory error, despite having 100 GB of free space on the hard drive. What is the problem?. Answer: Random-access memory (RAM) is used to manage and store data of actively running processes and applications.
◍ Which feature of an integrated development environment (IDE) adds a pause to a program to stop the flow of execution where it is defined by the user?. Answer: Breakpoints
◍ What is a page. Answer: A fixed-size block of logical (virtual) memory
◍ Which networking device can be programmed to make decisions to send packets from an input port to an output port based on IP addresses?.
◍ Which connection type can a system analyst or administrator use for internet VPN technology when setting up a wide area network (WAN)?. Answer: Fiber optic
◍ Which type of isolation do all virtualized containers employ?. Answer: Process
◍ What is an interrupt in I/O. Answer: A signal from a device to CPU indicating it needs attention or is ready
◍ Which operating system uses the Bourne-Again shell (bash) scripting tool?. Answer: Linux
◍ Why is the optimal algorithm not practical. Answer: It requires knowledge of future memory references, which is impossible to know
◍ Which type of storage devices are characterized by the fastest access times and data transfer rates?. Answer: Solid-state drives
◍ A printer is being configured on a network to print documents for users. Which role should the printer be configured for?. Answer: Server
◍ What is C-SCAN disk scheduling. Answer: Circular SCAN - head moves in one direction, then jumps back to beginning without servicing
◍ What is a cooked disk. Answer: A disk with a file system installed
◍ What is SCAN disk scheduling. Answer: Elevator algorithm - head moves in one direction servicing requests, then reverses
◍ What is a key similarity between RAM and memory cards?. Answer: They are solid-state.
◍ What is DoS (Denial of Service). Answer: An attack that overwhelms a system to make it unavailable to legitimate users
◍ Which type of non-functional requirement (NFR) stipulates that a program running on a Windows 10 operating system must be able to run on a Windows 11 operating system without any change in performance?. Answer: Portability
◍ What is physical memory. Answer: Actual RAM hardware installed in the computer
◍ A client recently experienced a hard drive failure and lost stored data. The client does not want to rely on a backup but does want to secure their data. Which RAID configuration does this client need?. Answer: RAID 1
◍ Which network security measure deals with encrypting the data as it traverses the network?. Answer: Confidentiality
◍ Which type of non-functional requirement (NFR) deals with how well a system and its data are protected against attacks?. Answer: Security
◍ What key type does symmetric encryption use. Answer: Private key (same secret key for both parties)
◍ What is disk transfer time. Answer: Time to actually read/write the data once the head is positioned
◍ An application is being configured to only make requests to a database on another computer. Which role will the application play in this scenario?. Answer: Client
◍ Which networking solution helps to distribute the traffic across multiple servers capable of fulfilling the same tasks?. Answer: Load balancing
◍ What is memory compaction. Answer: Shifting memory contents to place all free memory together in one large block, eliminating external fragmentation
◍ What is paging. Answer: Memory management technique that divides memory into fixed-size blocks called pages and frames
◍ Which type of virus intends to make itself difficult to detect or analyze?. Answer: Armored virus
◍ What is the correct network structure for local building connectivity?. Answer: LAN
◍ Which TCP/IP suite layer handles the transport control protocol (TCP)?. Answer: Transport
◍ What is the logical file system. Answer: Manages file metadata, directory structure, and file control blocks
◍ Which requirement should be understood when configuring a RAID 5 system for a client?. Answer: A minimum of three drives are required.
◍ Which cloud service meets the need for consolidating business services into a single site with centralized management with secure and isolated resources?. Answer: Private
◍ What is the layered file system structure (top to bottom). Answer: Application programs → Logical file system → File-organization module → Basic file system → I/O control → Devices
◍ What algorithm is an example of symmetric encryption. Answer: DES (Data Encryption Standard), also AES
◍ What is one reason why programmed I/O does not work well when the I/O device is a hard disk or a graphics display?. Answer: A complete instruction fetch-execute cycle must be performed to
transfer each I/O data word.
◍ What is an access list. Answer: A list stored with an OBJECT showing which users/domains can access it
◍ What is a feature of cloud-based operating systems?. Answer: They are primarily stateless.
◍ What is a trojan horse. Answer: Malicious software disguised as legitimate software
◍ Which cloud computing characteristic allows a provider to allocate shared resources to multiple clients according to their usage demand?. Answer: Resource pooling
◍ A hiring manager is interviewing a candidate to be part of a front-end development team. Which skill would be relevant to their job function?. Answer: TypeScript
◍ How can Dropbox be accessed. Answer: Web browser, desktop application, or mobile app
◍ What is the basic file system layer. Answer: Issues generic read/write commands to device drivers based on logical block addresses
◍ Which type of virus changes form to avoid detection?. Answer: Polymorphic virus
◍ What is the difference between stream cipher and block cipher. Answer: Stream cipher encrypts one bit/byte at a time; Block cipher encrypts fixed-size blocks (e.g., 128 bits)
◍ Which cloud feature allows different types of clients and devices to access the resources?. Answer: Broad network access
◍ How much memory is wasted on average according to the 50% rule.
