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.
A network administrator notices that users cannot access HTTPS websites after enabling SSL inspection. The firewall policy allows the traffic, and the certificate is trusted on the clients. What is the most likely cause?
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 the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The CA certificate used for SSL inspection is not trusted by the clients.
Option A is correct because the most likely cause is that the CA certificate used for SSL inspection is not trusted by the clients. Even if the firewall policy allows the traffic and the certificate is trusted on the clients, if the CA certificate used to generate the inspection certificate is not trusted, the clients will not trust the certificate presented by the firewall, resulting in HTTPS access failures.
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 CA certificate used for SSL inspection is not trusted by the clients.
Why this is correct
If the CA certificate is not trusted, clients will block HTTPS connections.
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 client's browser has a proxy configured incorrectly.
The policy allows traffic, so SSL inspection is likely enabled.
✗
The DNS server is not resolving the domain names.
Why it's wrong here
DNS issues would prevent connection, but the symptom is specific to HTTPS.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may assume that if the firewall policy allows traffic and the certificate is trusted, SSL inspection should work, but they overlook that the CA certificate used for inspection must be trusted by the clients, not just the server certificate.
Detailed technical explanation
How to think about this question
When SSL inspection is enabled, the firewall acts as a man-in-the-middle, decrypting and re-encrypting traffic. It presents a certificate signed by its own CA to the client. If the client does not trust the firewall's CA certificate (e.g., it is not installed in the Trusted Root Certification Authorities store), the browser will display a certificate error and block the connection. This is a common issue in enterprise environments where the CA certificate must be deployed via Group Policy or MDM.
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.
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 CA certificate used for SSL inspection is not trusted by the clients. — Option A is correct because the most likely cause is that the CA certificate used for SSL inspection is not trusted by the clients. Even if the firewall policy allows the traffic and the certificate is trusted on the clients, if the CA certificate used to generate the inspection certificate is not trusted, the clients will not trust the certificate presented by the firewall, resulting in HTTPS access failures.
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.
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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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