Cryptography & Network Security

JKSSB Sub-Inspector (Telecommunication) · Cyber Security & Legal Framework · 21 practice questions with answers and explanations: 13 Easy, 8 Medium, 0 Hard.

Sample questions

Sample Easy question 1

What does a firewall do?

  1. Filters incoming and outgoing network traffic according to rules
  2. Repairs corrupted disks
  3. Compresses files
  4. Cools the server room
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Answer: A. A firewall allows or blocks traffic between networks.

Sample Easy question 2

Which port number does HTTPS use by default?

  1. 25
  2. 21
  3. 443
  4. 80
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Answer: C. HTTPS uses TCP port 443; plain HTTP uses 80.

Sample Easy question 3

What does the term 'two-factor authentication' (2FA) mean?

  1. Verifying identity using two different kinds of proof, such as a password and an OTP
  2. Using two different usernames
  3. Logging in from two devices at once
  4. Entering the password twice
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Answer: A. The factors are something you know, have or are.

Sample Medium question 4

In public-key (asymmetric) cryptography, which key is used to decrypt a message sent to you?

  1. Your private key
  2. Your public key
  3. The sender's private key
  4. A shared session password
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Answer: A. Anyone can encrypt with your public key, but only your private key decrypts.

Sample Medium question 5

Which algorithm is a widely used public-key algorithm based on the difficulty of factoring large numbers?

  1. AES
  2. MD5
  3. RSA
  4. DES
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Answer: C. RSA security rests on the difficulty of factoring the product of two large primes.

Sample Medium question 6

What is the output length of the SHA-256 hash function?

  1. 160 bits
  2. 128 bits
  3. 512 bits
  4. 256 bits
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Answer: D. SHA-256 produces a 256-bit digest.

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