11. Consider the following consistency semantics:
1. Writes to an open file by a user are visible immediately to other users that have this file open.
2. Once a file is closed, the changes made to it are visible only in sessions starting later. Already open instances of the file do not reflect these changes.
3. A file has a single image that interleaves all accesses regardless of their origin.

Which of the above are used in UNIX file system?
(a) 1, 2 and 3
(b) 1 and 2 only
(c) 1 and 3 only
(d) 2 and 3 only

Answer: (c)

12. If a host broadcasts a frame that includes a source and destination hardware address, and its purpose is to assign IP addresses to itself, which protocol at the Network layer does the host use?
(a) RARP
(b) ARPA
(c) ICMP
(d) TCP

Answer: (a)

13. What range of addresses can be used in the first octet of a class 𝐵 network address?
(a) 1 – 126
(b) 1 – 127
(c) 128 – 190
(d) 128 – 191

Answer: (d)

14. The transport layer protocols used for real time multimedia, file transfer, 𝐷 𝐷𝐷𝐷 and 𝐸 -mail respectively are
(a) TCP, UDP, UDP and TCP
(b) TCP, UDP, TCP and UDP
(c) UDP, TCP, UDP and TCP
(d) UDP, TCP, TCP and UDP

Answer: (c)

15. In a LAN network every system is identified by
(a) Name
(b) MAC Address
(c) IP Address
(d) Serial number given by manufacturer

Answer: (c)

16. Maximum data rate of a channel for a noiseless 3-kHz binary channel is
(a) 3000 bps
(b) 6000 bps
(c) 9000 bps
(d) 15000 bps

Answer: (b)

17. Which of the following can be used for digital fingerprint of a file?
(a) Netstart
(b) Cryptcat
(c) Md5sum
(d) All of these

Answer: (c)

18. If a password hacker devised a system trying a password entry system by a program which ran once a second. How much time it would take to crack a password consisting of 4 out of the 24 alphabet letters?
(a) 40 ℎ𝑟 approximately
(b) 46 ℎ𝑟 approximately
(c) 52 ℎ𝑟 approximately
(d) 58 ℎ𝑟 approximately

Answer: (b)

19. Trojan-Horse programs are
(a) Legitimate programs that allow unauthorized access
(b) Hacker programs that do not show up on the system
(c) Do not work
(d) Immediately discovered

Answer: (a)

20. Consider the following statements regarding the block encryption algorithms:
1. Columnar Transportation Cipher is an example of block Cipher
2. One Cipher text block may depend on several plaintext letters
3. An error in the encryption process affects only that character

Which of the above statements are correct?
(a) 1, 2 and 3
(b) 1 and 2 only
(c) 1 and 3 only
(d) 2 and 3 only

Answer: (b)