Multiple
choices questions in Computer Networks, Computer Networks solved MCQ,
How does TCP and UDP work?, handling of corrupted data packets by TCP,
handling of retransmission by TCP, when does tcp retransmit, why does tcp retransmit
Computer Networks MCQ - TCP and retransmission of data packets
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1. Which of the following communication protocols ensures the sender to resend the message, if the sender did not receive an acknowledgement for a sent message?
a) Only TCP
b) Only UDP
c) Both TCP and UDP
d) Neither TCP nor UDP
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Answer: (a) Only TCP In Transmission Control Protocol (TCP), the sender will resend the message in case if the sender does not receive an acknowledgement for a sent message. Because of this TCP is referred as reliable communication protocol. Why do we say that the TCP connection is reliable?Transmission is made reliable via the use of sequence numbers and acknowledgments. Conceptually, each octet of data is assigned a sequence number. The sequence number of the first octet of data in a segment is transmitted with that segment and is called the segment sequence number. Segments also carry an acknowledgment number which is the sequence number of the next expected data octet of transmissions in the reverse direction. When the TCP transmits a segment containing data, it puts a copy on a retransmission queue and starts a timer; when the acknowledgment for that data is received, the segment is deleted from the queue. If the acknowledgment is not received before the timer runs out, the segment is retransmitted. [Reference] TCP guarantees the delivery of data and packets in the same order as they were sent. When does TCP retransmission occur? / Why does TCP retransmit?TCP retransmission occurs if the sender TCP did not receive an acknowledgement for the segment it sent to the receiver. TCP will resend the corrupted packets whereas UDP not. |
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