The correct answer is that an external host is scanning internal hosts for open port 80. This conclusion is drawn from the ASA syslog pattern showing multiple connection attempts from a single external source IP to the same internal destination IP and port, with the source port incrementing on each attempt—a classic signature of a TCP port scan. On the Cisco CyberOps Associate 200-201 exam, this question tests your ability to differentiate reconnaissance activity from normal traffic or denial-of-service attacks; a common trap is confusing a scan with a DoS, but a scan focuses on probing a single port across one or a few targets, while a DoS floods many destinations or consumes bandwidth. To spot a port scan detection syslog pattern, remember the “one-to-one, port-up” rule: one source, one destination, and rising source ports.
200-201 Security Policies and Procedures Practice Question
This 200-201 practice question tests your understanding of security policies and procedures. 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.
```
%ASA-4-106023: Deny tcp src outside:10.0.0.10/54321 dst inside:192.168.1.100/80 by access-group "OUTSIDE_IN"
%ASA-4-106023: Deny tcp src outside:10.0.0.10/54322 dst inside:192.168.1.100/80 by access-group "OUTSIDE_IN"
%ASA-4-106023: Deny tcp src outside:10.0.0.10/54323 dst inside:192.168.1.100/80 by access-group "OUTSIDE_IN"
```
Refer to the exhibit. A security analyst observes these syslog messages from an ASA firewall. Based on the messages, which type of activity is most likely occurring?
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 external host scanning internal hosts for open port 80
Option B is correct. The messages show multiple connection attempts from the same source IP to the same destination IP and port, with increasing source ports. This pattern indicates a port scan, specifically a TCP port scan against port 80. Option A is about hosts inside initiating connections. Option C would show success. Option D is for DoS, which would involve many destinations or bandwidth.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
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 inside host attempting to access a web server on the outside
Why it's wrong here
The src is outside, so it is an external host targeting an internal server.
✗
A denial of service attack flooding the firewall
Why it's wrong here
A DoS would likely involve many different sources or cause performance impact, not just three attempts.
✓
An external host scanning internal hosts for open port 80
Why this is correct
Multiple connection attempts to the same IP and port indicate a scan.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Static NAT maps one inside address to one outside address.
✗
Successful web traffic from an external client
Why it's wrong here
The syslog says 'Deny', so traffic is blocked, not successful.
Common exam traps
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
Static NAT maps one inside address to one outside address.
PAT allows many inside hosts to share one public address using ports.
Inside local and inside global describe the private and translated addresses.
NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
→Identify inside and outside interfaces first.
→Check whether the scenario needs static NAT, dynamic NAT or PAT.
→Do not confuse NAT matching ACLs with normal packet-filtering intent.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
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.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related 200-201 NAT questions on configuration and troubleshooting.
Security Policies and Procedures — This question tests Security Policies and Procedures — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: An external host scanning internal hosts for open port 80 — Option B is correct. The messages show multiple connection attempts from the same source IP to the same destination IP and port, with increasing source ports. This pattern indicates a port scan, specifically a TCP port scan against port 80. Option A is about hosts inside initiating connections. Option C would show success. Option D is for DoS, which would involve many destinations or bandwidth.
What should I do if I get this 200-201 question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related 200-201 NAT questions on configuration and troubleshooting.
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?
Static NAT maps one inside address to one outside address.
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