Which TCP feature helps ensure correct ordering and reliability by assigning sequence numbers to packets?

Which TCP feature helps ensure correct ordering and reliability by assigning sequence numbers to packets?

• A. Packet size optimization
• B. DNS caching
• C. Sequence numbering
• D. IP addressing

Answer: (C)

In TCP, keeping track of where each byte belongs is essential for both delivering data in order and ensuring it arrives reliably. To do that, TCP assigns a sequence number to every segment as it’s sent. The receiver uses these numbers to put the incoming data in the correct order, even if segments arrive out of order. If any segment is missing, the receiver can detect the gap and the sender will retransmit after not receiving the expected acknowledgment. This interplay of sequence numbers, acknowledgments, and the ability to retransmit is what makes TCP both ordered and reliable. Packet size optimization focuses on efficiency and throughput, not guaranteeing order or reliability. DNS caching speeds up name resolution, not data delivery. IP addressing handles routing at the network layer and doesn’t ensure data is delivered reliably or in order.

In TCP, keeping track of where each byte belongs is essential for both delivering data in order and ensuring it arrives reliably. To do that, TCP assigns a sequence number to every segment as it’s sent. The receiver uses these numbers to put the incoming data in the correct order, even if segments arrive out of order. If any segment is missing, the receiver can detect the gap and the sender will retransmit after not receiving the expected acknowledgment. This interplay of sequence numbers, acknowledgments, and the ability to retransmit is what makes TCP both ordered and reliable.

Packet size optimization focuses on efficiency and throughput, not guaranteeing order or reliability. DNS caching speeds up name resolution, not data delivery. IP addressing handles routing at the network layer and doesn’t ensure data is delivered reliably or in order.