- A
Set the application control action to 'block' for the application
Why wrong: Setting to block does not help detection; detection is separate from action.
- B
Add a custom application signature based on the traffic pattern
If the built-in signatures don't cover the custom app, a custom signature can be created.
- C
Disable flow-based inspection and use proxy-based only
Why wrong: Application control works in both modes; switching modes is not a standard troubleshooting step for detection.
- D
Ensure the application control profile is applied to the correct firewall policy
Without applying the profile, no detection occurs.
- E
Enable SSL deep inspection if the application uses encryption
If the application is encrypted, deep inspection is required to see the payload for signature matching.
Quick Answer
The answer is to enable SSL deep inspection if the application uses encryption, add a custom application signature, and ensure the traffic is not bypassing the FortiGate via a policy route or NAT. Application control on FortiGate identifies traffic by matching deep packet inspection signatures against payload patterns, not just port numbers; when a custom application runs on a non-standard port, the default signature database may miss it because the port-based heuristic is overridden, and encrypted traffic without SSL inspection remains opaque to the engine. On the Fortinet NSE 4 exam, this scenario tests your understanding that application control is signature-driven, not port-driven, and that custom applications require explicit signature creation or deep inspection to be detected—a common trap is assuming a port change alone will trigger detection. Remember the mnemonic “CIP”: Custom signature, Inspection (deep), and Policy path—three checks to ensure the traffic reaches the inspection engine.
NSE4 Security Profiles Practice Question
This NSE4 practice question tests your understanding of security profiles. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
An administrator is troubleshooting why an application control profile is not detecting a custom application that uses a non-standard port. The administrator wants to ensure the application is properly identified. Which THREE steps should the administrator take? (Choose three.)
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Add a custom application signature based on the traffic pattern
Application control relies on signatures that may require specific settings like 'deep inspection' for encrypted traffic, adding custom signatures, or ensuring the traffic is not bypassing the FortiGate. Additionally, using an application group can help organize custom signatures.
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.
- ✗
Set the application control action to 'block' for the application
Why it's wrong here
Setting to block does not help detection; detection is separate from action.
- ✓
Add a custom application signature based on the traffic pattern
Why this is correct
If the built-in signatures don't cover the custom app, a custom signature can be created.
Related concept
Static NAT maps one inside address to one outside address.
- ✗
Disable flow-based inspection and use proxy-based only
Why it's wrong here
Application control works in both modes; switching modes is not a standard troubleshooting step for detection.
- ✓
Ensure the application control profile is applied to the correct firewall policy
Why this is correct
Without applying the profile, no detection occurs.
Related concept
Static NAT maps one inside address to one outside address.
- ✓
Enable SSL deep inspection if the application uses encryption
Why this is correct
If the application is encrypted, deep inspection is required to see the payload for signature matching.
Related concept
Static NAT maps one inside address to one outside address.
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 NSE4 NAT questions on configuration and troubleshooting.
- →
Security Profiles — study guide chapter
Learn the concepts, then practise the questions
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Security Profiles practice questions
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FAQ
Questions learners often ask
What does this NSE4 question test?
Security Profiles — This question tests Security Profiles — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: Add a custom application signature based on the traffic pattern — Application control relies on signatures that may require specific settings like 'deep inspection' for encrypted traffic, adding custom signatures, or ensuring the traffic is not bypassing the FortiGate. Additionally, using an application group can help organize custom signatures.
What should I do if I get this NSE4 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 NSE4 NAT questions on configuration and troubleshooting.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
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Last reviewed: Jun 21, 2026
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.
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