Cyber Security — MCQ (Multiple Choice Questions)

Chapter 1: Cryptography

1. Which security service does a digital signature provide? a) Confidentiality b) Integrity and authentication c) Availability d) Non-repudiation

2. Which of the following is the key size used by AES-128? a) 64 bits b) 128 bits c) 256 bits d) 512 bits

3. A Caesar cipher with 26 letters has how many effective keys? a) 25 b) 26 c) 27 d) Infinite

4. Which hash function is considered broken and should not be used? a) SHA-256 b) SHA-3 c) MD5 d) BLAKE3

5. In public-key cryptography, which key is used to verify a signature? a) The signer's private key b) The signer's public key c) A shared secret d) A symmetric key

Chapter 2: Communication & Network Security

6. Which layer of the OSI model handles routing? a) Transport b) Network c) Data Link d) Session

7. Which wireless security protocol is considered secure today? a) WEP b) WPA c) WPA2 / WPA3 d) TKIP

8. In the TCP/IP model, which layer is roughly equivalent to the OSI Network layer? a) Application b) Transport c) Internet d) Network Interface

9. An IP address that reads the same on a local and remote capture is an example of: a) Interruption b) Interception c) Modification d) Fabrication

10. Which topology uses a single shared backbone? a) Star b) Ring c) Bus d) Mesh

Chapter 3: Information Security Concepts

11. Which factor is "something you have"? a) Password b) Fingerprint c) Hardware token d) Face

12. An IDS that alerts when traffic deviates from a learned baseline is: a) Misuse-based b) Signature-based c) Anomaly-based d) Stateful

13. In a confusion matrix, an alert that fires on a normal packet is called: a) True positive b) True negative c) False negative d) False positive

14. A worm differs from a virus mainly because: a) A worm needs a host file; a virus does not b) A virus needs a host file; a worm does not c) A worm encrypts files; a virus does not d) A virus spreads over the network; a worm does not

15. Which of these is a passive attack? a) Buffer overflow b) Replay attack c) Sniffing d) DNS spoofing

Chapter 4: Security Threats & Vulnerabilities

16. Which password is strongest? a) 123456 b) password c) P@ssw0rd d) Tr0ub4dor&3 (long, mixed) — assume equal length here the long random passphrase is best

17. A buffer overflow primarily lets an attacker: a) Read encrypted traffic b) Hijack control flow / execute code c) Slow down the network d) Bypass the firewall

18. Which attack uses many compromised machines to flood a victim? a) Phishing b) Man-in-the-middle c) DDoS d) Spoofing

19. Which file system mechanism best defends against ransomware? a) Regular online backups only b) Regular offline/immutability backups + least privilege c) A longer password d) Disabling the firewall

20. Insider threats are harder to detect than external threats because: a) Insiders move faster b) Insiders already have legitimate access, so their misuse looks normal c) Insiders use encrypted channels d) Insiders own the hardware

Practice questions (21–30)

21. Which access-control model grants access based on security clearances and data labels (e.g., Top Secret)? a) Role-based (RBAC) b) Mandatory (MAC) c) Discretionary (DAC) d) Attribute-based (ABAC)

22. In PKI, what signs a certificate? a) The subject's private key b) The subject's public key c) The issuing CA's private key d) The issuing CA's public key

23. Which of these is NOT part of the CIA triad? a) Confidentiality b) Integrity c) Authentication d) Availability

24. A firewall that filters packets based only on IP addresses and ports (no payload inspection) is: a) Packet-filtering b) Stateful inspection c) Application-layer d) Proxy

25. In TLS, symmetric encryption is used for: a) The bulk data after the handshake b) The handshake key exchange only c) Nothing; TLS is fully asymmetric d) Password authentication only

26. Which malware spreads on its own, needs no host file, and needs no user action? a) Virus b) Worm c) Trojan horse d) Rootkit

27. The key difference between symmetric and asymmetric encryption is: a) Symmetric uses one key; asymmetric uses a public/private pair b) Asymmetric is faster for large files c) Symmetric cannot encrypt text d) Asymmetric needs no key

28. A man-in-the-middle attack is best defended by authenticating the endpoints, e.g., with: a) A longer password b) Digital signatures c) Disabling the firewall d) A stronger router

29. The security principle "least privilege" directly reduces the impact of: a) DDoS b) Privilege escalation c) Phishing d) Replay

30. In the classic risk formula Risk = Threat × Vulnerability × Impact, lowering any one factor: a) Has no effect b) Reduces risk c) Moves risk to another system d) Eliminates risk

Answers (key only)

Reveal answers after attempting the questions

1-b, 2-b, 3-a, 4-c, 5-b, 6-b, 7-c, 8-c, 9-b, 10-c, 11-c, 12-c, 13-d, 14-b, 15-c, 16-d, 17-b, 18-c, 19-b, 20-b, 21-b, 22-c, 23-c, 24-a, 25-a, 26-b, 27-a, 28-b, 29-b, 30-b.