- A
The deny policy at ID 5 is matching the traffic before the allow policy at ID 10
Since ID 5 has a lower numeric value, it is evaluated first. The source 192.168.10.0/24 is a subset of 192.168.0.0/16, so deny matches.
- B
The allow policy at ID 10 will override the deny policy because it is more specific
Why wrong: FortiGate does not use 'most specific match'; it uses first match. The first matched policy (deny) wins.
- C
The traffic will be matched by the implicit deny at the end of the policy list
Why wrong: The traffic is already denied by policy ID 5, so it does not reach the implicit deny.
- D
The administrator should enable 'policy override' on the allow policy
Why wrong: There is no 'policy override' feature; policy order is determined by sequence number.
- E
The administrator should change the deny policy's source to exclude 192.168.10.0/24 or move the allow policy above ID 5
To allow the traffic, the deny policy must not match the desired subnet, or the allow policy must be placed before the deny policy.
Quick Answer
The correct answer is that the administrator should either change the deny policy’s source to exclude 192.168.10.0/24 or move the allow policy above ID 5. This is correct because FortiGate firewall policies are evaluated sequentially from top to bottom based on their policy ID, meaning traffic is matched against the first policy whose criteria it meets. Since policy ID 5 is a deny rule covering the broader 192.168.0.0/16 range, it catches the 192.168.10.0/24 traffic before the more specific allow policy at ID 10 is ever reached. On the Fortinet NSE 4 Network Security Professional exam, this concept tests your understanding of policy order and subnet specificity—a common trap is assuming a more specific allow rule will override a broader deny rule placed above it. Remember the memory tip: “First match wins, so order your policies from specific to general, or keep your denies narrow.”
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.
An administrator is troubleshooting why traffic from a specific subnet (192.168.10.0/24) to the internet is not being matched by the expected firewall policy. The policy list shows an allow policy for this traffic at ID 10, but there is a deny policy at ID 5 for any traffic from 192.168.0.0/16. Which TWO statements are correct?
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
The deny policy at ID 5 is matching the traffic before the allow policy at ID 10
Option A is correct because FortiGate firewall policies are evaluated sequentially from top to bottom based on their policy ID. Since policy ID 5 (deny for 192.168.0.0/16) appears before policy ID 10 (allow for 192.168.10.0/24), traffic from 192.168.10.0/24 is matched by the broader deny policy first, and the allow policy is never reached. This is a fundamental behavior of FortiGate's policy lookup order.
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 deny policy at ID 5 is matching the traffic before the allow policy at ID 10
Why this is correct
Since ID 5 has a lower numeric value, it is evaluated first. The source 192.168.10.0/24 is a subset of 192.168.0.0/16, so deny matches.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
The allow policy at ID 10 will override the deny policy because it is more specific
Why it's wrong here
FortiGate does not use 'most specific match'; it uses first match. The first matched policy (deny) wins.
- ✗
The traffic will be matched by the implicit deny at the end of the policy list
Why it's wrong here
The traffic is already denied by policy ID 5, so it does not reach the implicit deny.
- ✗
The administrator should enable 'policy override' on the allow policy
Why it's wrong here
There is no 'policy override' feature; policy order is determined by sequence number.
- ✓
The administrator should change the deny policy's source to exclude 192.168.10.0/24 or move the allow policy above ID 5
Why this is correct
To allow the traffic, the deny policy must not match the desired subnet, or the allow policy must be placed before the deny policy.
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 often assume firewall policies use a 'most specific match' logic like routing, but FortiGate strictly uses sequential first-match based on policy ID order.
Detailed technical explanation
How to think about this question
FortiGate firewall policies are processed in ascending order of policy ID, and the first matching policy is applied (first-match, not best-match). This is different from routing tables, which use longest prefix match. In real-world scenarios, administrators must carefully plan policy IDs to ensure more specific allow policies are placed before broader deny policies, or use address objects with proper exclusions to avoid unintended blocks.
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
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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: The deny policy at ID 5 is matching the traffic before the allow policy at ID 10 — Option A is correct because FortiGate firewall policies are evaluated sequentially from top to bottom based on their policy ID. Since policy ID 5 (deny for 192.168.0.0/16) appears before policy ID 10 (allow for 192.168.10.0/24), traffic from 192.168.10.0/24 is matched by the broader deny policy first, and the allow policy is never reached. This is a fundamental behavior of FortiGate's policy lookup order.
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.
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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