200-201 Network Intrusion Analysis Practice Question
An analyst is reviewing a PCAP and observes a TCP stream where the client sends a packet with the PSH and ACK flags set, containing an HTTP GET request. The server responds with a packet with the FIN and ACK flags set, but the client continues to send data. Later, the client sends a packet with the RST flag set. Which statement best describes what is happening?
⚠ Common exam trap
The trap here is interpreting the RST as a separate attack, when it is actually the client's response to the server's FIN after ignoring it and continuing to send data.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The server is initiating a graceful connection termination, but the client is ignoring it and continuing to send data, eventually forcing a reset.
The server's FIN+ACK indicates it wants to close its half of the connection. The client should respond with a FIN and stop sending data. Instead, the client continues to send data, which is a TCP protocol violation. The eventual RST from the client abruptly terminates the connection. This behavior could be due to a buggy application, a misconfigured client, or a deliberate attempt to cause a reset.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
The server is initiating a graceful connection termination, but the client is ignoring it and continuing to send data, eventually forcing a reset.
Why this is correct
The server sends FIN+ACK to start a graceful close, meaning it has no more data to send. The client, however, continues to transmit data, which is a violation of TCP half-close semantics. Eventually, the client sends an RST, abruptly terminating the connection. This could indicate a malfunctioning client or an attempt to disrupt the session.
- ✗
The client is using TCP fast open, which allows data transmission after the server sends FIN.
Why it's wrong here
TCP fast open is a mechanism to reduce latency by allowing data in the SYN packet, not after a FIN. The server's FIN indicates it is closing its half of the connection. Sending data after receiving a FIN is not part of TCP fast open and is considered a protocol violation.
- ✗
The server is experiencing a denial-of-service condition because the client is flooding it with data after the FIN.
Why it's wrong here
While the client continues to send data after the server's FIN, the scenario does not indicate a flood or DoS condition. The client eventually sends an RST, which terminates the connection. A DoS would involve overwhelming traffic, not a single stream with a few packets.
- ✗
The client is performing a TCP reset attack to terminate the connection prematurely.
Why it's wrong here
A TCP reset attack involves an attacker spoofing an RST packet to terminate a connection between two hosts. In this scenario, the RST is sent by the client itself, not a third party, and it occurs after the server initiated a FIN. This is not a classic reset attack but rather an abnormal client behavior.
Visual reference
About these practice questions
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Cisco exam blueprint
This 200-201 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 200-201 exam.