What does the Transport Layer do if a segment is lost during transmission (in TCP)?

Question

Accepted Answer

Requests retransmission - In the Transport Layer of the OSI model, the protocol TCP (Transmission Control Protocol) is responsible for ensuring reliable data delivery between devices.

If a segment (a piece of data) is lost during transmission, TCP automatically detects this using its acknowledgment system and requests the sender to retransmit the lost segment.

This ensures that the receiving device gets all the data in the correct order and without errors. TCP uses sequence numbers and acknowledgments to track segments. If the receiver does not acknowledge a segment within a certain time, the sender assumes it was lost and resends it.

Key points about TCP segment loss handling:

TCP provides reliable data transfer using acknowledgments.
If an acknowledgment is not received, TCP triggers retransmission.
It ensures complete and ordered delivery of all segments.
Used in critical applications like emails, websites, and file transfers where every piece of data matters.


Conclusion: The correct answer is Requests retransmission. TCP handles segment loss by asking the sender to resend the missing data, ensuring reliability in communication. This concept is very important for understanding how reliable networking works and is frequently asked in interviews.

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