The answer is that the traffic will be allowed because no entry exists for high severity. This occurs because the IPS sensor action configuration in FortiGate only applies to severity levels that are explicitly defined; when a high-severity signature is detected but no corresponding action is set, the sensor defaults to a "pass" or allow behavior while still generating a log entry. On the Fortinet NSE 4 Network Security Professional exam, this concept tests your understanding that IPS sensor actions are not inherited or assumed—each severity level must be individually configured to block, reset, or quarantine traffic. A common trap is assuming that high-severity threats are automatically blocked, but the default is to allow and log unless you specify otherwise. Memory tip: "No rule means let it through—log it, don't stop it."
NSE4 Security Profiles Practice Question
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
end
next
end
Given the above IPS sensor configuration, what will happen when traffic matching a high-severity IPS signature is detected?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The traffic will be allowed because no entry exists for high severity.
Option D is correct because the IPS sensor configuration shown does not include an entry for high-severity signatures. Without a specific action defined for high severity, the sensor defaults to allowing the traffic while still generating a log entry. This is a common behavior in FortiGate IPS where only explicitly configured severity levels have defined actions.
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 traffic will be logged but not blocked.
Why it's wrong here
No logging is configured for high severity.
✗
The traffic will be blocked only if the signature is enabled globally.
Why it's wrong here
Global settings do not affect the sensor's behavior.
✗
The traffic will be blocked because the sensor has a block action.
Why it's wrong here
The block action only applies to medium severity signatures.
✓
The traffic will be allowed because no entry exists for high severity.
Why this is correct
High-severity signatures are not in the sensor, so they are allowed.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume high-severity signatures are automatically blocked by default, but FortiGate requires explicit action configuration per severity level, and the default action is to allow.
Detailed technical explanation
How to think about this question
FortiGate IPS sensors use a severity-based action matrix where each severity level (critical, high, medium, low, info) can have an independent action (block, monitor, pass, or default). When no action is explicitly set for a severity, the sensor applies the 'default' action, which is to allow the traffic and log it. This behavior is defined in the IPS sensor configuration under config ips sensor, where the 'entries' subcommand sets per-severity actions. In real-world deployments, failing to configure high-severity actions can leave critical threats unblocked, making this a common misconfiguration.
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 traffic will be allowed because no entry exists for high severity. — Option D is correct because the IPS sensor configuration shown does not include an entry for high-severity signatures. Without a specific action defined for high severity, the sensor defaults to allowing the traffic while still generating a log entry. This is a common behavior in FortiGate IPS where only explicitly configured severity levels have defined actions.
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.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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This NSE4 practice question is part of Courseiva's free Fortinet 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 NSE4 exam.
Question Discussion
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