EmSAT Achieve (UAE) · Computer Science

Computer Systems, Networks and Cybersecurity

26 practice questions, each with the answer and an explanation.

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Random questions from this topic, one at a time. You see the answer and the explanation straight after each one.

All 26 questions

  1. What is the decimal equivalent of the hexadecimal number 2F₁₆?
  2. In computer architecture, which component of the central processing unit (CPU) directs system operations and manages the fetch-decode-execute cycle?
  3. Which layer of the OSI reference model is responsible for end-to-end process-to-process communication, flow control, and error recovery using protocols such as TCP and UDP?
  4. What is the 8-bit two's complement binary representation of the decimal integer -6?
  5. Which cryptographic algorithm is an asymmetric (public-key) cipher commonly used for secure key exchange and digital signatures?
  6. In Boolean algebra, what is the simplified equivalent of the expression NOT(A AND B) according to De Morgan's laws?
  7. How many total usable host IP addresses are available in an IPv4 subnet configured with the subnet mask /28 (255.255.255.240)?
  8. What type of cybersecurity vulnerability occurs when an application includes unsanitized user input directly inside a database query string?
  9. Which network protocol automatically assigns dynamic IP addresses, default gateways, and DNS server configurations to host devices joining a local area network?
  10. In computer systems, what is the primary role of the Translation Lookaside Buffer (TLB)?
  11. What type of malware is self-replicating and spreads across computer networks autonomously without requiring user intervention or attaching to a host file?
  12. What is the primary operational distinction between Transmission Control Protocol (TCP) and User Datagram Protocol (UDP)?
  13. How many total unique bit patterns can be encoded using an 8-bit byte?
  14. Which logic gate produces an output of HIGH (1) if and only if its two binary inputs have differing values (one HIGH and one LOW)?
  15. In public-key cryptography (asymmetric encryption), which key is used by a sender to encrypt a confidential message intended exclusively for recipient Alice?
  16. Which type of computer memory is volatile, losing all stored data immediately when electrical power is switched off?
  17. What is the standard port number assigned by IANA for encrypted HTTPS web traffic over Transport Layer Security?
  18. What cryptographic primitive produces a fixed-length output string from arbitrary-sized input data such that it is computationally infeasible to invert or find collisions?
  19. What is the primary function of the Address Resolution Protocol (ARP) in a local area network?
  20. Which attack type occurs when an adversary intercepts, monitors, or secretly alters communication packets passing between two legitimate communicating endpoints without their knowledge?
  21. What is the two's complement value of the binary byte 11110000 interpreted as a signed 8-bit integer?
  22. Which cybersecurity framework element is designed to isolate an internal trusted network from untrusted external traffic by inspecting incoming and outgoing packets against security rules?
  23. What is the primary function of the Program Counter (PC) register in the CPU architecture?
  24. Which character encoding standard uses variable-width encoding (1 to 4 bytes per character) and is backward-compatible with 7-bit ASCII?
  25. What social engineering attack involves crafting fraudulent emails impersonating reputable institutions to manipulate users into disclosing confidential passwords or credentials?
  26. In computer networking, which protocol is responsible for mapping human-readable domain names (such as u.ae) into numerical IP addresses?

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