121. Consider three IP networks A, B and C. Host HA in network A sends messages each containing 180 bytes of application data to a host HC in network C. The TCP layer prefixes a 20 byte header to the message. This passes through an intermediate net­work B. The maximum packet size, including 20 byte IP header, in each network is A : 1000 bytes B : 100 bytes C : 1000 bytes The network A and B are connected through a 1 Mbps link, while B and C are connected by a 512 Kbps link (bps = bits per second).
Assuming that the packets are correctly delivered, how many bytes, including headers, are delivered to the IP layer at the destination for one application message, in the best case ? Consider only data packets.
a. 200
b. 220
c. 240
d. 260
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Answer: (d).260

122. Consider three IP networks A, B and C. Host HA in network A sends messages each containing 180 bytes of application data to a host HC in network C. The TCP layer prefixes a 20 byte header to the message. This passes through an intermediate net­work B. The maximum packet size, including 20 byte IP header, in each network is A : 1000 bytes B : 100 bytes C : 1000 bytes The network A and B are connected through a 1 Mbps link, while B and C are connected by a 512 Kbps link (bps = bits per second).
What is the rate at which application data is transferred to host HC? Ignore errors, acknowledgements, and other overheads.
a. 325.5 Kbps
b. 354.5 Kbps
c. 409.6 Kbps
d. 512.0 Kbps
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Answer: (b).354.5 Kbps

123. Which of the following protocol is called as byte-oriented protocol?
a. Sliding Window Protocol
b. TCP
c. UDP
d. HDLC
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Answer: (b).TCP

124. If syn = 0 and ack = 1, it indicates
a. Open connection packet
b. Open connection ack
c. Data packet
d. None of these
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Answer: (c).Data packet

125. A DNS.....................server gets its data from another DNS server.
a. Primary
b. Secondary
c. Root
d. All of these
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Answer: (b).Secondary

126. The .............................field in the MIME header describes the method used to encode the data.
a. Content – type
b. Content – transfer – Encoding
c. Content – ID
d. Content – description
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Answer: (b).Content – transfer – Encoding

127. A client message usually needs ........................ to send mail.
a. SMTP
b. POP
c. Both a and b
d. None of these
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Answer: (c).Both a and b

128. Which one is not a method of HTTP?
a. PATCH
b. OPTION
c. UNLINK
d. CUT
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Answer: (d).CUT

129. Which one of the following is a communication protocol used for email?
a. X.400
b. FTAM
c. SNMP
d. EDI
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Answer: (a).X.400

130. Which one of the following statement about email is false?
a. Communication takes place at the convenience of both the sender and the receiver
b. Messages can be Include text, graphics audio and video
c. A historical record of messages can be kept
d. Files can be attached to messages
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Answer: (a).Communication takes place at the convenience of both the sender and the receiver