What does a TCP segment provide that allows the destination to assemble segments in the correct order?

What does a TCP segment provide that allows the destination to assemble segments in the correct order?

• A. Sequence numbers
• B. Error detection
• C. Window size
• D. Acknowledgments

Answer: (A)

TCP uses sequence numbers to ensure data can be put back together in the original order. Each segment carries the sequence number of its first data byte in the overall byte stream, so the receiver can place every byte at its correct position even if segments arrive out of order. When gaps are detected, the receiver knows what’s missing and can trigger retransmission via acknowledgments. While checksums provide integrity, and the window size controls flow, and acknowledgments confirm receipt, the sequence numbers are what actually enable correct reassembly.

TCP uses sequence numbers to ensure data can be put back together in the original order. Each segment carries the sequence number of its first data byte in the overall byte stream, so the receiver can place every byte at its correct position even if segments arrive out of order. When gaps are detected, the receiver knows what’s missing and can trigger retransmission via acknowledgments. While checksums provide integrity, and the window size controls flow, and acknowledgments confirm receipt, the sequence numbers are what actually enable correct reassembly.