Which of the following is not a field in TCP header ?
2023
Which of the following is not a field in TCP header ?
- A.
Sequence Number
- B.
Checksum
- C.
Fregmentation offset
- D.
Window size
Attempted by 564 students.
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Correct answer: C
Answer: The field "Fregmentation offset" (fragmentation offset) is not part of the TCP header.
Key TCP header fields and brief descriptions:
Source port and Destination port: identify the sending and receiving application endpoints.
Sequence Number: indicates the sequence number of the first byte in this segment for ordered delivery and retransmission control.
Acknowledgment Number: when the ACK flag is set, it specifies the next expected byte from the other side.
Data Offset, Reserved, and Flags: indicate header length and control bits (e.g., SYN, ACK, FIN).
Window Size: used for flow control to advertise the receiver's available buffer space.
Checksum: verifies the integrity of the TCP header and payload (including a pseudo-header).
Urgent Pointer and Options/Padding: optional fields for urgent data and extended options.
Why the fragmentation offset is not a TCP field:
The fragmentation offset is an IPv4 header field used to indicate the position of a fragment within the original IP datagram so fragments can be reassembled. It is part of the IP-layer header, not the TCP header which operates at the transport layer.