This NSE4 practice question tests your understanding of security profiles. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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.
config ips sensor
edit "sensor1"
config entries
edit 1
set severity medium
set action block
next
edit 2
set severity critical
set action block
next
end
next
end
Refer to the exhibit. An administrator has created an IPS sensor with two entries. The first entry sets severity 'medium' and action 'block'. The second entry sets severity 'critical' and action 'block'. What will happen when a packet triggers an IPS signature with severity 'low'?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "first"
Why it matters: Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
Refer to the exhibit.
config ips sensor
edit "sensor1"
config entries
edit 1
set severity medium
set action block
next
edit 2
set severity critical
set action block
next
end
next
end
A
The packet will be allowed (pass).
Signatures not matching any entry use the default action 'pass'.
B
The packet will be logged and a session will be created.
Why wrong: Logging is not configured; no log action is set.
C
The packet will be blocked if the signature severity is 'low' or 'high'.
Why wrong: Only severities defined in entries are processed; 'low' is not defined.
D
The packet will be blocked because the sensor is enabled.
Why wrong: The sensor only blocks signatures with explicitly configured severity.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The packet will be allowed (pass).
The IPS sensor in the exhibit defines rules only for severity 'medium' and 'critical', both with action 'block'. When a packet triggers a signature with severity 'low', it does not match any entry in the sensor. Therefore, the default action for unmatched signatures is to allow (pass) the traffic. FortiGate IPS sensors apply actions only to explicitly configured severity levels; unlisted severities are not affected.
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 packet will be allowed (pass).
Why this is correct
Signatures not matching any entry use the default action 'pass'.
Clue confirmation
The clue word "first" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The packet will be logged and a session will be created.
Why it's wrong here
Logging is not configured; no log action is set.
✗
The packet will be blocked if the signature severity is 'low' or 'high'.
Why it's wrong here
Only severities defined in entries are processed; 'low' is not defined.
✗
The packet will be blocked because the sensor is enabled.
Why it's wrong here
The sensor only blocks signatures with explicitly configured severity.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume an enabled IPS sensor blocks all traffic by default, but FortiGate IPS sensors only apply actions to signatures whose severity is explicitly listed in the sensor entries.
Detailed technical explanation
How to think about this question
FortiGate IPS sensors use a first-match logic: when a packet triggers a signature, the sensor checks entries in order. If no entry matches the signature's severity, the packet is processed according to the default IPS action, which is 'pass' (allow). This behavior is defined in the FortiOS IPS engine, where each signature has a fixed severity (low, medium, high, critical) and the sensor only overrides actions for explicitly configured severities. In a real-world scenario, an administrator might intentionally leave 'low' severity unblocked to reduce false positives while still blocking medium and critical threats.
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 Profiles — This question tests Security Profiles — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The packet will be allowed (pass). — The IPS sensor in the exhibit defines rules only for severity 'medium' and 'critical', both with action 'block'. When a packet triggers a signature with severity 'low', it does not match any entry in the sensor. Therefore, the default action for unmatched signatures is to allow (pass) the traffic. FortiGate IPS sensors apply actions only to explicitly configured severity levels; unlisted severities are not affected.
What should I do if I get this NSE4 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: "first". Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
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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