- A
A deny policy with a lower policy ID is matching the traffic before the allow policy
FortiGate evaluates policies sequentially from top to bottom. If a deny policy appears earlier in the list, it will match and block the traffic before reaching the allow policy.
- B
The firewall policy has an incorrect source interface
Why wrong: While possible, the admin would typically verify interface settings if present; the most common issue is policy ordering.
- C
The policy is disabled
Why wrong: The admin confirmed the policy is present via the command, but did not check if it is enabled.
- D
The web server is not responding to HTTP requests
Why wrong: The question asks for the MOST likely cause related to firewall policy; server-side issues are less likely given the scenario.
Quick Answer
The answer is a deny policy with a lower policy ID matching the traffic before the allow policy. This is the most likely cause because FortiGate processes firewall policies in sequential order based on policy ID, from lowest to highest, and the first matching policy is applied. Even though the allow policy is present and visible in the kernel list via the diagnose firewall iprope list command, a deny policy with a lower ID that also matches the same source, destination, and service will intercept the HTTP traffic first, blocking it before the allow rule is ever evaluated. On the Fortinet NSE 4 exam, this scenario tests your understanding of policy ordering and the kernel policy list, a common trap where candidates assume a policy’s presence guarantees it will be matched. A useful memory tip: think of FortiGate policies like a bouncer at a door—the first bouncer (lowest ID) who says “no” stops you, even if a later bouncer would say “yes.”
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 network administrator creates a firewall policy allowing HTTP traffic from the internal network to a web server in the DMZ. Users report that they cannot access the web server. The administrator runs 'diagnose firewall iprope list' and sees the policy is present. What is the MOST likely cause of the issue?
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
A deny policy with a lower policy ID is matching the traffic before the allow policy
The 'diagnose firewall iprope list' command confirms the allow policy exists in the FortiGate's kernel policy list, meaning it is present and enabled. However, FortiGate evaluates policies in sequential order based on policy ID (lowest first), so a deny policy with a lower ID that matches the same traffic (e.g., from internal to DMZ) will be hit first, blocking the HTTP request before the allow policy can be evaluated. This is the most likely cause because the policy is present but not being matched due to ordering.
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.
- ✓
A deny policy with a lower policy ID is matching the traffic before the allow policy
Why this is correct
FortiGate evaluates policies sequentially from top to bottom. If a deny policy appears earlier in the list, it will match and block the traffic before reaching the allow policy.
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 firewall policy has an incorrect source interface
Why it's wrong here
While possible, the admin would typically verify interface settings if present; the most common issue is policy ordering.
- ✗
The policy is disabled
Why it's wrong here
The admin confirmed the policy is present via the command, but did not check if it is enabled.
- ✗
The web server is not responding to HTTP requests
Why it's wrong here
The question asks for the MOST likely cause related to firewall policy; server-side issues are less likely given the scenario.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume 'policy is present' means it is working, but FortiGate's policy order (lowest ID first) means a lower-ID deny policy can override a higher-ID allow policy even if both match the same traffic.
Trap categories for this question
Command / output trap
The admin confirmed the policy is present via the command, but did not check if it is enabled.
Scenario analysis trap
The question asks for the MOST likely cause related to firewall policy; server-side issues are less likely given the scenario.
Detailed technical explanation
How to think about this question
FortiGate uses a sequential policy lookup where the first matching policy (by policy ID) is applied, and subsequent policies are ignored. The 'diagnose firewall iprope list' command displays the kernel-level policy chain, which includes both enabled and disabled policies but only active ones are evaluated; a lower-ID deny policy will preempt the allow policy even if the allow policy is correctly configured. In real-world scenarios, this often happens when a default 'deny all' policy (e.g., ID 1) is placed before a more specific allow policy (e.g., ID 2), or when an administrator adds a new allow policy but forgets to adjust the order.
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 security administrator must allow nursing staff to reach a patient records server while blocking access from the guest Wi-Fi VLAN. After applying an extended ACL, traffic is still blocked from nursing workstations. The ACL was applied outbound instead of inbound on the wrong interface. Questions like this test ACL direction and placement rules.
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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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: A deny policy with a lower policy ID is matching the traffic before the allow policy — The 'diagnose firewall iprope list' command confirms the allow policy exists in the FortiGate's kernel policy list, meaning it is present and enabled. However, FortiGate evaluates policies in sequential order based on policy ID (lowest first), so a deny policy with a lower ID that matches the same traffic (e.g., from internal to DMZ) will be hit first, blocking the HTTP request before the allow policy can be evaluated. This is the most likely cause because the policy is present but not being matched due to ordering.
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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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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