This section contains more frequently asked cryptography and network security mcqs in the various competitive exams.

PRACTICE IT NOW TO SHARPEN YOUR CONCEPT AND KNOWLEDGE

1. Main function of proxy application gateway firewall is

  • to allow corporate users to use efficiently all internet services
  • to allow intranet users to securely use specified internet services
  • to allow corporate users to use all internet services
  • to prevent corporate users from using internet services

2. Proxy application gateway
(i) acts on behalf of all intranet users wanting to access internet securely
(ii)monitors all accesses to internet and allows access to only specified IP addresses
(iii) disallows use of certain protocols with security problems
(iv) disallows all internet users from accessing intranet

  • i, ii
  • i, ii, iii
  • i, ii, iii, iv
  • ii, iii, iv

3. A hardened firewall host on an intranet
(i) has a proxy application gateway program running on it
(ii)Allows specified internet users to access specified services in the intranet
(iii) Initiates all internet activities requested by clients and monitors them
(iv) prevents outsiders from accessing IP addresses within the intranet

  • i, ii
  • i, ii, iii
  • i, ii, iii, iv
  • ii, iii, iv

4. A hardened firewall host on an Intranet is

  • a software which runs in any of the computers in the intranet
  • a software which runs on a special reserved computer on the intranet
  • a stripped down computer connected to the intranet
  • a mainframe connected to the intranet to ensure security

5. By encryption of a text we mean

  • compressing it
  • expanding it
  • scrambling it to preserve its security
  • hashing it

6. Encryption is required to
(i) protect business information from eavesdropping when it is transmitted on internet
(ii) efficiently use the bandwidth available in PSTN
(iii) to protect information stored in companies’ databases from retrieval
(iv) to preserve secrecy of information stored in databases if an unauthorized person retrieves it

  • i and ii
  • ii and iii
  • iii and iv
  • i and iv

7. Encryption can be done

  • only on textual data
  • only on ASCII coded data
  • on any bit string
  • only on mnemonic data

8. By applying permutation (31254) and substitution by 5 characters away from current character (A Æ F , B Æ G etc..) the following string ABRACADABRA becomes

  • FGWCAAADRBF
  • RABCAAADRBF
  • WFGHFFFIWGF
  • None of the above

9. The following ciphertext was received. The plaintext was permuted using permutation (34152) and substitution. Substitute character by character +3 (A Æ D, etc). The plain text after decryption is: Cipher text :PDLJDLXHVQC

  • MAIGAIUESNZ
  • IAMAGENIUSZ
  • LDPDJHPLXVZ
  • IAMAGENIUSC

10. By symmetric key encryption we mean

  • one private key is used for both encryption and decryption
  • private and public key used are symmetric
  • only public keys are used for encryption
  • only symmetric key is used for encryption
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