The correct interpretation is that an attacker is performing a port scan on internal hosts from the outside. This conclusion is drawn from the firewall logs showing multiple denied TCP connection attempts from a single external IP address to various internal IPs across different ports such as 80, 443, and 22. This sequential, multi-destination probing pattern is the hallmark of a port scan, where an attacker systematically checks for open services to exploit. On the Cisco CyberOps Associate 200-201 exam, this scenario tests your ability to distinguish reconnaissance activity from a legitimate single connection or a denial-of-service attack. A common trap is confusing a port scan with a brute-force attack, but remember that scans target many ports or hosts, not repeated logins on one service. The rule OUTSIDE_IN correctly blocking these attempts confirms the firewall is functioning as designed. Memory tip: think “one source, many destinations and ports” to spot a scan.
200-201 Security Concepts Practice Question
This 200-201 practice question tests your understanding of security concepts. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. 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
Refer to the exhibit.
```
Mar 1 12:34:56.789: %ASA-5-111008: User 'admin' executed the 'configure terminal' command.
Mar 1 12:35:01.123: %ASA-4-106023: Deny tcp src outside:192.0.2.10/12345 dst inside:10.0.0.1/80 by access-group "OUTSIDE_IN" [0x0, 0x0]
Mar 1 12:35:05.456: %ASA-4-106023: Deny tcp src outside:192.0.2.10/12346 dst inside:10.0.0.2/443 by access-group "OUTSIDE_IN" [0x0, 0x0]
```
Refer to the exhibit. A network analyst sees these firewall logs. What is the most likely interpretation?
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
✓
An attacker is performing a port scan on internal hosts from the outside
The firewall logs show multiple denied TCP connection attempts from a single external IP to various internal IPs on different ports (e.g., 80, 443, 22). This pattern of sequential probes across multiple destinations and ports is characteristic of a port scan, where an attacker systematically probes for open services. The rule OUTSIDE_IN is correctly logging and blocking these attempts, indicating the firewall is functioning as designed to prevent reconnaissance.
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.
✓
An attacker is performing a port scan on internal hosts from the outside
Why this is correct
Repeated denies from same source to different destinations on common ports indicate a scan.
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 firewall rule OUTSIDE_IN is misconfigured and blocking all traffic
Why it's wrong here
Only specific denies are shown, not all traffic.
✗
A malware is trying to phone home to an external C2 server
Why it's wrong here
Traffic is inbound, not outbound.
✗
A user is trying to access internal web servers legitimately but is blocked by ACL
Why it's wrong here
Multiple ports to different destinations suggest scanning, not normal access.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the distinction between a port scan (multiple destinations/ports from one source) and a C2 beacon (single destination, periodic traffic), where candidates mistakenly interpret any blocked external traffic as malware callbacks.
Trap categories for this question
Command / output trap
Only specific denies are shown, not all traffic.
Detailed technical explanation
How to think about this question
Port scans often use TCP SYN packets (half-open scans) to avoid complete connections, but firewalls with stateful inspection can still log and block these by tracking connection states. The logs show 'DENY' entries, which typically correspond to ACL rules that drop packets before state table entries are created. In real-world scenarios, attackers may use tools like Nmap with timing options (e.g., -T2) to evade detection, but consistent logging of denied packets from a single source is a strong indicator 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.
Security Concepts — This question tests Security Concepts — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: An attacker is performing a port scan on internal hosts from the outside — The firewall logs show multiple denied TCP connection attempts from a single external IP to various internal IPs on different ports (e.g., 80, 443, 22). This pattern of sequential probes across multiple destinations and ports is characteristic of a port scan, where an attacker systematically probes for open services. The rule OUTSIDE_IN is correctly logging and blocking these attempts, indicating the firewall is functioning as designed to prevent reconnaissance.
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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