The correct answer is a port scan, specifically a SYN scan. This is identified by observing multiple TCP SYN packets sent to a single host, such as 10.10.10.10, targeting different ports like 80, 443, 22, and 21, with no subsequent ACK or RST responses completing the three-way handshake. In a normal connection, the client would respond to a SYN-ACK with an ACK, but here the sender never finishes the handshake, instead moving on to probe the next port. On the Cisco CyberOps Associate 200-201 exam, this pattern tests your ability to recognize reconnaissance activity in packet captures, often appearing as a scenario where you must distinguish a scan from a legitimate connection attempt. A common trap is confusing this with a half-open scan, but remember: a connect() scan completes the handshake and then sends an RST, whereas this SYN scan never completes it. Memory tip: “SYN alone, no ACK in sight—that’s a scan, not a handshake right.”
200-201 Network Intrusion Analysis Practice Question
This 200-201 practice question tests your understanding of network intrusion analysis. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Exhibit
09:32:45.123456 IP 10.0.0.5.12345 > 192.168.1.1.80: Flags [S], seq 12345
09:32:45.123789 IP 192.168.1.1.80 > 10.0.0.5.12345: Flags [S.], seq 54321, ack 12346
09:32:45.124000 IP 10.0.0.5.12345 > 192.168.1.1.80: Flags [R], seq 12346
Refer to the exhibit. What does this packet capture indicate?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Port scan
The packet capture shows multiple TCP SYN packets sent to a single host (10.10.10.10) targeting different ports (80, 443, 22, 21) with no subsequent ACK or RST responses. This pattern is characteristic of a port scan, specifically a SYN scan, where the attacker sends SYN packets to probe for open ports without completing the three-way handshake.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
SYN flood
Why it's wrong here
Incorrect. A SYN flood would not complete the handshake.
Read the scenario before looking for a memorised answer.
✗
Session hijack
Why it's wrong here
Incorrect. Session hijacking involves spoofing and does not end with RST.
✗
Normal HTTP traffic
Why it's wrong here
Incorrect. Normal traffic would continue with HTTP requests, not an immediate RST.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the distinction between a SYN flood (volume-based attack on a single port) and a SYN scan (probing multiple ports), where candidates mistakenly associate any SYN traffic with a flood rather than recognizing the multi-port pattern as reconnaissance.
Detailed technical explanation
How to think about this question
A SYN scan (half-open scan) sends a SYN packet and, upon receiving a SYN-ACK, sends a RST to tear down the connection, avoiding full session establishment. This technique is stealthier than a full connect scan and is commonly used by tools like Nmap (with -sS flag) to map open ports without logging in application logs. The absence of any SYN-ACK or RST in the capture suggests the target may be filtering or dropping responses, but the pattern of sequential SYN packets to distinct ports remains diagnostic of scanning activity.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Network Intrusion Analysis — This question tests Network Intrusion Analysis — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Port scan — The packet capture shows multiple TCP SYN packets sent to a single host (10.10.10.10) targeting different ports (80, 443, 22, 21) with no subsequent ACK or RST responses. This pattern is characteristic of a port scan, specifically a SYN scan, where the attacker sends SYN packets to probe for open ports without completing the three-way handshake.
What should I do if I get this 200-201 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. Given a packet capture showing TCP packets with flags: first packet SYN, second packet SYN-ACK, third packet ACK, then a fourth packet with RST flag. What should the analyst suspect?
hard
✓ A.Port scan
B.Normal traffic
C.SYN flood
D.Denial of service
Why A: The three-way handshake (SYN, SYN-ACK, ACK) completes a TCP connection, but the immediate RST after the ACK indicates the client terminated the connection without sending any application data. This pattern is characteristic of a port scan (e.g., using nmap's connect scan), where the scanner verifies the port is open by completing the handshake and then immediately resets to avoid leaving the connection half-open.
Last reviewed: Jun 25, 2026
Question Discussion
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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.
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