Which TCP header field is used to order segments?

Which TCP header field is used to order segments?

• A. Sequence Number
• B. Checksum
• C. Flow Control
• D. Destination Port

Answer: (A)

TCP keeps a reliable stream by ordering data with sequence numbers. Each segment carries a sequence number that indicates the position of the first data byte within the overall TCP connection’s byte stream. Since segments can arrive out of order or get delayed, the receiver uses these sequence numbers to place bytes in the correct order and to detect any missing data. This sequencing is what lets TCP reassemble the stream accurately and know exactly where new data fits in. The other fields have different roles: the checksum checks data integrity but does not determine order; flow control (the window) tells the sender how much data can be sent before waiting for an acknowledgment; the destination port identifies which application should receive the data.

TCP keeps a reliable stream by ordering data with sequence numbers. Each segment carries a sequence number that indicates the position of the first data byte within the overall TCP connection’s byte stream. Since segments can arrive out of order or get delayed, the receiver uses these sequence numbers to place bytes in the correct order and to detect any missing data. This sequencing is what lets TCP reassemble the stream accurately and know exactly where new data fits in.

The other fields have different roles: the checksum checks data integrity but does not determine order; flow control (the window) tells the sender how much data can be sent before waiting for an acknowledgment; the destination port identifies which application should receive the data.