- A
The FortiGate is using a proxy server that caches different results for different users
Why wrong: FortiGate's explicit proxy could cause different behavior, but the question implies transparent proxy.
- B
The web filter profile is configured to 'allow' but the FortiGuard rating is inconsistent
Why wrong: FortiGuard rating is consistent across same categories.
- C
The firewall policy has an FQDN destination that resolves to different IPs for different users due to DNS load balancing
Why wrong: The destination is likely the same; DNS resolution happens once per session.
- D
Some users have a different web filter profile applied due to a policy ordering issue where a higher-priority policy matches their traffic
If a policy with a lower policy ID does not have the web filter profile, traffic matching that policy will bypass the intended filtering.
NSE4 Firewall Policies and NAT Practice Question
This NSE4 practice question tests your understanding of firewall policies and nat. 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 configures a firewall policy to allow outbound HTTP traffic and applies a web filter profile. The admin notices that some users can access a known malicious URL while others are blocked. All users are in the same source subnet (10.0.1.0/24). What is the MOST likely cause of this inconsistent behavior?
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
Some users have a different web filter profile applied due to a policy ordering issue where a higher-priority policy matches their traffic
Option D is correct because when multiple firewall policies match traffic from the same source subnet, FortiGate uses the first matching policy in order (lowest policy ID). If a higher-priority policy with a different web filter profile matches some users' traffic (e.g., based on source port or application), those users will have different filtering behavior. This is a classic policy ordering issue where the intended web filter profile is not applied consistently to all users in the same subnet.
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 FortiGate is using a proxy server that caches different results for different users
Why it's wrong here
FortiGate's explicit proxy could cause different behavior, but the question implies transparent proxy.
- ✗
The web filter profile is configured to 'allow' but the FortiGuard rating is inconsistent
Why it's wrong here
FortiGuard rating is consistent across same categories.
- ✗
The firewall policy has an FQDN destination that resolves to different IPs for different users due to DNS load balancing
Why it's wrong here
The destination is likely the same; DNS resolution happens once per session.
- ✓
Some users have a different web filter profile applied due to a policy ordering issue where a higher-priority policy matches their traffic
Why this is correct
If a policy with a lower policy ID does not have the web filter profile, traffic matching that policy will bypass the intended filtering.
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.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume all traffic from the same subnet is treated identically, overlooking that FortiGate policy matching is first-match and can differentiate based on other attributes like source port or user identity, leading to inconsistent profile application.
Detailed technical explanation
How to think about this question
FortiGate firewall policies are evaluated in sequential order based on policy ID, and the first match is applied. When multiple policies match the same source subnet but differ in other criteria (e.g., source port, schedule, or user/group), users with different characteristics may match different policies. The web filter profile is bound to the policy, so inconsistent application of profiles is a direct result of policy ordering and matching logic. In flow-based inspection, the web filter profile is applied per session, so the policy match determines the profile used.
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.
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Firewall Policies and NAT — study guide chapter
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FAQ
Questions learners often ask
What does this NSE4 question test?
Firewall Policies and NAT — This question tests Firewall Policies and NAT — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Some users have a different web filter profile applied due to a policy ordering issue where a higher-priority policy matches their traffic — Option D is correct because when multiple firewall policies match traffic from the same source subnet, FortiGate uses the first matching policy in order (lowest policy ID). If a higher-priority policy with a different web filter profile matches some users' traffic (e.g., based on source port or application), those users will have different filtering behavior. This is a classic policy ordering issue where the intended web filter profile is not applied consistently to all users in the same subnet.
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
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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.
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