1) If a 2000 byte data message is sent using TFTP, the corresponding Ethernet packet will be of
__ bytes.

Answer: 2050

Solution: (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.

2) 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

Answer: b

Solution: The HLEN field contains the size of the IP header in multiples of 32 bits or 4
bytes. Here, size of the IP header = 192 bits = 6 x 32 bits. Hence, HLEN will contain 0110, which
is the binary equivalent of the number 6.

3) The maximum size of data that can be accommodated in an IP datagram is __ bytes.

Answer: 65515

Solution: The TOTAL-LENGTH field in the IP header is 16 bits, which can contain values from 0 to 2
16 – 1 = 65535, the total size of an IP packet can be 65535 bytes. Also, the minimum size of the IP header is 20 bytes, which makes the maximum size of data as 65535 – 20 = 65515 bytes.

4) Which of the following statements are false?

a. Datagram is faster than virtual circuits if the number of packets transmitted is small.
b. Datagram is faster than virtual circuits if the number of packets transmitted is large.
c. In circuit switching, a dedicated communication path is established between two end stations.
d. Datagram does not require connection establishment phase.

Answer: b

Solution: Virtual circuits have the initial overhead of connection establishment, but once
it is done, packets will flow faster as the header size is smaller. Datagrams do not require
connection establishment. For less number of packets, the overhead will dominate, and hence
datagram will be faster. For large number of packets, however, virtual circuit will become faster
as the overhead per packet becomes less. Also, in circuit switching, a dedicated communication
path is established between two end stations. Hence, only option (b) is false.

5) 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.

Answer: a, d

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.