This 200-201 practice question tests your understanding of security monitoring. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
A security analyst for a medium-sized enterprise is monitoring the network using Cisco Stealthwatch. They notice a sudden spike in traffic originating from an internal host (IP 10.10.10.50) communicating with multiple external IP addresses on port 445 (SMB). The host is a Windows server that typically serves web applications on ports 80 and 443. The analyst checks the host's firewall logs and finds that Windows Firewall is disabled. The host's antivirus is up to date and no alerts were triggered. The traffic pattern shows multiple connection attempts to /24 subnets across the internet, each with a single packet per destination. Based on this behavior, what is the most likely issue?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The host is infected with malware that is performing network reconnaissance.
The traffic pattern—multiple connection attempts to /24 subnets across the internet, each with a single packet per destination—is classic behavior for network reconnaissance, specifically scanning for open SMB ports. The host's Windows Firewall being disabled and the lack of antivirus alerts indicate that the host is likely compromised and running malware that is performing this reconnaissance, as legitimate scanning or DDoS amplification would not exhibit this single-packet-per-destination pattern.
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.
✓
The host is infected with malware that is performing network reconnaissance.
Why this is correct
The pattern matches malware scanning for SMB vulnerabilities (e.g., EternalBlue).
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The host is part of a distributed vulnerability scanning initiative.
Why it's wrong here
No indication of authorization; also the host's typical function is web serving, not scanning.
✗
The host is being used for a DDoS amplification attack.
Why it's wrong here
DDoS amplification uses spoofed sources and large responses; here traffic is scanning many destinations.
✗
The host is legitimately scanning the internet for outdated SMB shares.
Why it's wrong here
Legitimate scans would be authorized and typically use more targeted ranges.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the distinction between reconnaissance (scanning) and attack (exploitation/DDoS), where candidates may confuse the single-packet scanning pattern with DDoS amplification or legitimate scanning, but the key is the lack of handshake completion and the disabled firewall indicating compromise.
Detailed technical explanation
How to think about this question
Cisco Stealthwatch uses NetFlow or IPFIX data to analyze traffic patterns; a single packet per destination is a telltale sign of a TCP SYN scan (half-open scan) where the scanner sends a SYN packet and does not complete the handshake, avoiding connection logs. Port 445 is commonly targeted by worms like EternalBlue (MS17-010) that spread via SMB, and a disabled Windows Firewall removes the host's primary defense against such lateral movement. In real-world incidents, this pattern often precedes ransomware deployment or data exfiltration.
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.
Security Monitoring — This question tests Security Monitoring — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The host is infected with malware that is performing network reconnaissance. — The traffic pattern—multiple connection attempts to /24 subnets across the internet, each with a single packet per destination—is classic behavior for network reconnaissance, specifically scanning for open SMB ports. The host's Windows Firewall being disabled and the lack of antivirus alerts indicate that the host is likely compromised and running malware that is performing this reconnaissance, as legitimate scanning or DDoS amplification would not exhibit this single-packet-per-destination pattern.
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.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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