The answer is that without SSL deep inspection, FortiGate cannot inspect encrypted HTTPS traffic to match application signatures. This is because application control relies on analyzing the unencrypted payload of network traffic to identify applications like Facebook or Twitter, but HTTPS encrypts the entire session, including the application-layer data. On the Fortinet NSE 4 Network Security Professional exam, this scenario tests your understanding that application control alone is insufficient for blocking encrypted applications—decryption via SSL deep inspection is a prerequisite. A common trap is assuming application signatures can magically see through encryption, but they cannot; the firewall only sees the encrypted tunnel, not the content inside. Remember the memory tip: “No decrypt, no detect”—if the traffic is encrypted and deep inspection is off, application control is blind to the application inside.
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 configures an application control profile to block 'Facebook' and 'Twitter' using application signatures. Users can still access Facebook via HTTPS. The firewall policy has application control enabled and SSL deep inspection is not configured. Why is Facebook not blocked?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
HTTPS traffic is encrypted and cannot be inspected without SSL deep inspection
Option A is correct: Without SSL deep inspection, FortiGate cannot see the encrypted application payload to match application signatures for HTTPS traffic. Application control requires decryption for encrypted applications.
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.
✗
The application signature for Facebook is not updated
Why it's wrong here
Even if updated, cannot inspect encrypted traffic.
✗
The application control profile is configured in monitor-only mode
Why it's wrong here
Monitor mode would log but not block; the question says block is configured.
✓
HTTPS traffic is encrypted and cannot be inspected without SSL deep inspection
Why this is correct
Application signatures rely on payload; encryption hides that.
Related concept
Static NAT maps one inside address to one outside address.
✗
Facebook uses a non-standard port that application control does not monitor
Why it's wrong here
Facebook typically uses port 443, which is monitored.
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 — 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: HTTPS traffic is encrypted and cannot be inspected without SSL deep inspection — Option A is correct: Without SSL deep inspection, FortiGate cannot see the encrypted application payload to match application signatures for HTTPS traffic. Application control requires decryption for encrypted applications.
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.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. An administrator configures an application control profile to block social media applications. Users can still access Facebook and Twitter via web browsers. What is the most likely reason?
medium
A.The application signatures for Facebook and Twitter are not up to date
✓ B.The firewall policy has SSL/SSH inspection set to 'certificate-inspection' instead of 'deep-inspection'
C.The application control profile is set to 'monitor' instead of 'block'
D.The firewall policy is configured with flow-based inspection
Why B: Application control relies on signatures to detect applications. If deep inspection is not enabled, encrypted traffic may not be identified correctly.
Variation 2. A network administrator configures an application control profile to block social media applications. Users can still access Facebook through a web browser. What is the MOST likely reason?
medium
A.The application signatures are outdated
✓ B.Application control is not enabled for HTTPS traffic without deep inspection
C.The firewall policy is in proxy-based mode
D.The application control profile is not applied to the correct policy
Why B: Option A is correct. Application control requires deep inspection to identify applications in encrypted traffic.
Last reviewed: Jun 21, 2026
Question Discussion
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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.
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