The answer is creating IPS filters to whitelist specific traffic patterns. This is correct because when you tune IPS on a FortiGate, excluding trusted source IP addresses from certain signatures directly prevents the engine from generating alerts for traffic known to be legitimate, which is the core mechanism for reducing false positives. On the Fortinet NSE 4 Network Security Professional NSE4 exam, this concept tests your understanding of how to balance security with operational efficiency—a common trap is assuming that disabling a signature entirely is the best fix, when in fact a targeted whitelist filter preserves protection for other traffic. A strong memory tip is to think of the “trusted source” filter as a surgical scalpel, not a sledgehammer: you carve out exceptions for benign traffic without removing the signature’s overall detection capability.
NSE4 Security Profiles Practice Question
This NSE4 practice question tests your understanding of security profiles. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.
Which THREE factors should be considered when tuning IPS to reduce false positives?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Excluding trusted source IP addresses from certain signatures.
Option A is correct because excluding trusted source IP addresses from certain signatures prevents the IPS from generating alerts for traffic that is known to be legitimate, directly reducing false positives. This is a common tuning technique in FortiGate IPS where you can create exceptions for specific sources or destinations to avoid unnecessary alerts from benign traffic.
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.
✓
Excluding trusted source IP addresses from certain signatures.
Why this is correct
Excluding known good traffic reduces false positives.
Related concept
Read the scenario before looking for a memorised answer.
✗
Enabling hardware acceleration for IPS processing.
Why it's wrong here
Hardware acceleration improves performance, not false positives.
✗
Increasing the sensitivity of signatures to catch more attacks.
Why it's wrong here
Increasing sensitivity may increase false positives.
✓
Adjusting the severity threshold for which signatures generate alerts.
Why this is correct
Raising the threshold can reduce alerts for low-severity matches.
Related concept
Read the scenario before looking for a memorised answer.
✓
Creating IPS filters to whitelist specific traffic patterns.
Why this is correct
Whitelisting known benign patterns reduces false positives.
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 often confuse performance optimization (hardware acceleration) with accuracy tuning, or mistakenly think that increasing sensitivity reduces false positives, when in fact it does the opposite.
Detailed technical explanation
How to think about this question
FortiGate IPS uses a combination of signature-based detection and protocol decoders to inspect traffic. When tuning to reduce false positives, you can leverage the IPS filter feature to whitelist specific traffic patterns (Option E) or adjust the severity threshold (Option D) so that only high-severity alerts are generated, filtering out low-severity false positives. In real-world scenarios, a common practice is to create a custom IPS sensor with exceptions for trusted internal servers (e.g., DNS or NTP servers) that may trigger false positives due to their normal behavior.
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: Excluding trusted source IP addresses from certain signatures. — Option A is correct because excluding trusted source IP addresses from certain signatures prevents the IPS from generating alerts for traffic that is known to be legitimate, directly reducing false positives. This is a common tuning technique in FortiGate IPS where you can create exceptions for specific sources or destinations to avoid unnecessary alerts from benign traffic.
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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Question Discussion
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