Which protocol uses sequence numbers to ensure ordered data delivery?

Which protocol uses sequence numbers to ensure ordered data delivery?

• A. UDP
• B. ICMP
• C. TCP
• D. IP

Answer: (C)

TCP uses sequence numbers to keep track of bytes as they move from sender to receiver. Each byte in the data stream gets a sequence number, and segments carry the numbers for the bytes they contain. This lets the receiving side reorder segments that arrive out of order and detect any missing data. Acknowledgments confirm what was received, and if something doesn’t arrive in time, the sender can retransmit. All of this together provides reliable, in-order delivery and helps control the flow of data so the sender doesn’t overwhelm the receiver. Other protocols don’t guarantee this behavior in the same way. UDP is connectionless and does not guarantee delivery or order. IP handles packets on a best-effort basis without built-in sequencing or reliability. ICMP is used for control and error messaging, not for delivering application data.

TCP uses sequence numbers to keep track of bytes as they move from sender to receiver. Each byte in the data stream gets a sequence number, and segments carry the numbers for the bytes they contain. This lets the receiving side reorder segments that arrive out of order and detect any missing data. Acknowledgments confirm what was received, and if something doesn’t arrive in time, the sender can retransmit. All of this together provides reliable, in-order delivery and helps control the flow of data so the sender doesn’t overwhelm the receiver.

Other protocols don’t guarantee this behavior in the same way. UDP is connectionless and does not guarantee delivery or order. IP handles packets on a best-effort basis without built-in sequencing or reliability. ICMP is used for control and error messaging, not for delivering application data.