- A
The web server's certificate is self-signed and FortiGate is rejecting the connection
Why wrong: A certificate error would typically block or warn on the connection, not silently bypass antivirus scanning.
- B
The antivirus profile is configured for flow-based inspection instead of proxy-based
Why wrong: Both flow and proxy modes can scan HTTPS if SSL inspection is enabled. This is not the root cause.
- C
SSL/TLS deep inspection is not enabled on the firewall policy
HTTPS traffic is encrypted. FortiGate cannot inspect the payload without SSL deep inspection decrypting the TLS session. The antivirus profile requires inspection mode to be enabled.
- D
The FortiGuard antivirus subscription has expired
Why wrong: An expired subscription would typically still scan with old signatures, and the symptom would be different — the profile would still attempt scanning.
Quick Answer
The answer is that SSL/TLS deep inspection is not enabled on the firewall policy. This is the most likely reason HTTPS traffic is not being scanned by the antivirus profile because HTTPS encrypts the payload with SSL/TLS, making the content invisible to security tools. Without deep inspection—also called SSL inspection or HTTPS decryption—the FortiGate can only see encrypted packets, so even with antivirus enabled in the policy, it cannot inspect the data for malware. On the Fortinet NSE 4 exam, this question tests your understanding that antivirus profiles require decrypted traffic to function; a common trap is assuming that simply enabling antivirus in the policy is sufficient. Remember the key principle: encrypted traffic must be decrypted before it can be scanned. A useful memory tip is “No decrypt, no detect”—if SSL inspection is off, antivirus is blind to HTTPS threats.
NSE4 System and Network Administration Practice Question
This NSE4 practice question tests your understanding of system and network administration. 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.
A FortiGate admin notices that HTTPS traffic to a web server is not being scanned by the antivirus profile applied to the firewall policy. The admin confirms the policy is correct and antivirus is enabled. What is the MOST likely reason the traffic is not being scanned?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"most likely"Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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
SSL/TLS deep inspection is not enabled on the firewall policy
HTTPS traffic is encrypted with SSL/TLS, so an antivirus profile cannot inspect the payload unless the firewall can decrypt the traffic. Even with antivirus enabled in the policy, without SSL/TLS deep inspection (also called SSL inspection or HTTPS decryption), FortiGate only sees encrypted packets and cannot scan for malware. Therefore, the most likely reason is that SSL/TLS deep inspection is not enabled on the firewall policy.
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 web server's certificate is self-signed and FortiGate is rejecting the connection
Why it's wrong here
A certificate error would typically block or warn on the connection, not silently bypass antivirus scanning.
- ✗
The antivirus profile is configured for flow-based inspection instead of proxy-based
- ✓
SSL/TLS deep inspection is not enabled on the firewall policy
Why this is correct
HTTPS traffic is encrypted. FortiGate cannot inspect the payload without SSL deep inspection decrypting the TLS session. The antivirus profile requires inspection mode to be enabled.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
The FortiGuard antivirus subscription has expired
Why it's wrong here
An expired subscription would typically still scan with old signatures, and the symptom would be different — the profile would still attempt scanning.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume antivirus profiles automatically inspect all traffic, forgetting that encrypted HTTPS requires explicit SSL/TLS decryption before any content inspection can occur.
Detailed technical explanation
How to think about this question
FortiGate uses a proxy-based SSL inspection engine to terminate the TLS connection, re-encrypt traffic, and then apply UTM profiles like antivirus. Without an SSL inspection profile that defines a CA certificate and decryption rules, the FortiGate cannot decrypt the HTTPS stream, so the antivirus scanner sees only ciphertext. In real-world deployments, administrators must generate or import a CA certificate and configure an SSL inspection profile (e.g., deep-inspection or certificate-inspection) in the firewall policy to enable decryption.
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 practitioner preparing for the NSE4 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
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.
- →
System and Network Administration — study guide chapter
Learn the concepts, then practise the questions
- →
System and Network Administration practice questions
Targeted practice on this topic area only
- →
All NSE4 questions
1,000 questions across all exam domains
- →
Fortinet NSE 4 Network Security Professional NSE4 study guide
Full concept coverage aligned to exam objectives
- →
NSE4 practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Related NSE4 practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
System and Network Administration practice questions
Practise NSE4 questions linked to System and Network Administration.
Firewall Policies and NAT practice questions
Practise NSE4 questions linked to Firewall Policies and NAT.
Authentication and VPN practice questions
Practise NSE4 questions linked to Authentication and VPN.
Security Profiles practice questions
Practise NSE4 questions linked to Security Profiles.
High Availability and Diagnostics practice questions
Practise NSE4 questions linked to High Availability and Diagnostics.
NSE4 fundamentals practice questions
Practise NSE4 questions linked to NSE4 fundamentals.
NSE4 scenario practice questions
Practise NSE4 questions linked to NSE4 scenario.
NSE4 troubleshooting practice questions
Practise NSE4 questions linked to NSE4 troubleshooting.
Practice this exam
Start a free NSE4 practice session
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
FAQ
Questions learners often ask
What does this NSE4 question test?
System and Network Administration — This question tests System and Network Administration — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: SSL/TLS deep inspection is not enabled on the firewall policy — HTTPS traffic is encrypted with SSL/TLS, so an antivirus profile cannot inspect the payload unless the firewall can decrypt the traffic. Even with antivirus enabled in the policy, without SSL/TLS deep inspection (also called SSL inspection or HTTPS decryption), FortiGate only sees encrypted packets and cannot scan for malware. Therefore, the most likely reason is that SSL/TLS deep inspection is not enabled on the firewall policy.
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: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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 →
Same concept, more angles
1 more ways this is tested on NSE4
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. A FortiGate admin notices that HTTPS traffic to a web server is not being scanned by the antivirus profile applied to the firewall policy. The admin confirms the policy is correct and antivirus is enabled. What is the MOST likely reason the traffic is not being scanned?
medium- A.The web server's certificate is self-signed and FortiGate is rejecting the connection
- B.The FortiGuard antivirus subscription has expired
- C.The antivirus profile is configured for flow-based inspection instead of proxy-based
- ✓ D.SSL/TLS deep inspection is not enabled on the firewall policy
Why D: Option B is correct because HTTPS uses TLS encryption. Without SSL deep inspection enabled on the policy, FortiGate cannot decrypt and inspect the content of HTTPS traffic. The antivirus profile will only scan unencrypted traffic or traffic where deep inspection has decrypted it first.
Last reviewed: Jun 24, 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.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.