ETHICAL HACKING (NOC19-CS68)
ASSIGNMENT 1
QUESTION 1:
For which of the following, the tester is provided only with partial information about a network?
a. White box model
b. Black box model
c. Gray box model
d. None of these
Correct Answer: c
Detail Solution: In the white box model, the tester has complete information about the network. In the black box model, the tester does not have any information about the network. Gray box testing is somewhere in between, where the tester is only provided with partial information about the network.
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QUESTION 2:
Which of the following is/are not true about a packet switched network?
a. A communication link can be shared by more than one connection.
b. A communication link is dedicated to a connection.
c. The packet transfer delay between a pair of nodes is more or less constant.
d. The packet transfer delay between a pair of nodes may vary with time.
Correct Answer: b, c
Detail Solution: In a circuit switched network, a communication link remains dedicated to a connection; however, in a packet switched network, communication links may be shared by more than one connection. Also, in a packet switched network, packets between the same source and destination may follow different paths, and hence the packet transfer delay can vary with time. Thus, options (b) and (c) are false.
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QUESTION 3:
A 1000 byte packet is sent over a 50 kilo-bits-per-second (Kbps) point-to-point link whose propagation delay is 10 msec. The packet will reach the destination after ________ msec. (Assume 1K = 1000)
Correct Answer: 170
Detail Solution: 50x1000 = 50000 bits per second can be transferred through the link.
1 bit can be sent in = (1/50000) sec
1000 byte or 8000 bits can be sent in 8000 / 50000 sec = 0.16 sec = 160 msec
Hence the packet will reach the destination after = 160 msec + 10 msec = 170 msec
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QUESTION 4:
Which of the following OSI layers are host-to-host layers?
a. Session layer
b. Transport layer
c. Network layer
d. Datalink layer
Correct Answer: a, b
Detail Solution: Follows from Week-1, slide no 54. The layers transport, session, presentation and application are host-to-host layers, while the remaining three are not.
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QUESTION 5:
How many bits are there in the IP address and port number?
a. 32, 16
b. 32, 8
c. 48, 16
d. 48, 8
Correct Answer: a
Detail Solution: IP address in IPv4 is 32 bits long, whereas port numbers in TCT or UDP are 16 bits long.
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QUESTION 6:
Which of the following are true for the TCP protocol?
a. It provides connection-oriented, reliable packet transfer service.
b. It provides connection-less datagram service.
c. All packets from a source to a destination follow the same path.
d. Packets from a source to a destination may follow different paths.
Correct Answer: a, d
Detail Solution: TCP ensures connection-oriented and reliable message transfer service between two hosts. However, it runs on top of the IP protocol for packet delivery, which is a datagram based service and hence individual packets constituting the message may follow different paths. Hence the options (a) and (d) are true.
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QUESTION 7:
If a 2000 byte data message is sent using TFTP, the corresponding Ethernet packet will be of ________ bytes.
Correct Answer: 2050
Detail Solution: Follows from Week-1, slide no 65. (H-Eth + H-IP + H-UDP + H-TFTP + T-Eth) field bytes are added to get 50 bytes. Hence the total size of the Ethernet packet will be 2000+50 = 2050 bytes.
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QUESTION 8:
If the IP header is 192 bits long, what will be the value of the “HLEN” field?
a. 4
b. 6
c. 32
d. 192
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