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101 · Question #474
101 Question #474: Real Exam Question with Answer & Explanation
The correct answer is C: The server is temporary unable to receive any more data. A TCP window size of zero is a flow control signal from the sender of that packet, indicating its receive buffer is full and it cannot accept more data at that moment.
Question
A BIO IP Administrator is troubleshooting a slow web application. A packet capture shows that some of the packets coming from a window size of zero. A packet capture shows that som a window size of zero. What does this mean?
Options
- AThe client is trying to close the TCP connection
- BThe server is trying to close the TCP connection
- CThe server is temporary unable to receive any more data
- DThe client is temporarily unable to receive any more data
Explanation
A TCP window size of zero is a flow control signal from the sender of that packet, indicating its receive buffer is full and it cannot accept more data at that moment.
Common mistakes.
- A. TCP connection teardown initiated by the client uses a FIN flag in the TCP header, not a window size of zero.
- B. A server-initiated connection close is signaled by a FIN or RST flag, not by advertising a zero window size.
- D. If the client were temporarily unable to receive data, it would be the client sending packets with a window size of zero, not the server; the question states the zero-window packets are coming from the server side.
Concept tested. TCP flow control and zero window advertisement
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