The answer is that the Deny-All policy is placed above the Allow-HTTP policy, causing the traffic to be denied before it can match the permit rule. This is because FortiGate firewall policies are evaluated sequentially from top to bottom, and the first matching policy is applied to the traffic. When a Deny-All rule sits above a more specific Allow rule, all traffic that matches the broader deny condition—such as traffic from the 10.0.0.0/8 subnet to the internet on HTTP—will be blocked immediately, never reaching the intended Allow-HTTP policy. On the Fortinet NSE 4 exam, this classic policy ordering issue tests your understanding of rule precedence and the importance of placing explicit allow rules above a final implicit or explicit deny. A common trap is assuming that a more specific allow rule will override a general deny, but in FortiGate, order always wins over specificity. Remember the memory tip: “Allow first, deny last—or your traffic won’t pass.”
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.
Exhibit
config firewall policy
edit 0
set name "Deny-All"
set srcintf "any"
set dstintf "any"
set srcaddr "all"
set dstaddr "all"
set action deny
set schedule "always"
set service "ALL"
set logtraffic all
next
edit 1
set name "Allow-HTTP"
set srcintf "internal"
set dstintf "wan1"
set srcaddr "10.0.0.0/8"
set dstaddr "all"
set action accept
set schedule "always"
set service "HTTP"
set logtraffic all
next
end
Refer to the exhibit. An administrator configures the policies as shown. Traffic from 10.0.0.0/8 to the internet on HTTP is denied. What is the most likely reason?
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.
config firewall policy
edit 0
set name "Deny-All"
set srcintf "any"
set dstintf "any"
set srcaddr "all"
set dstaddr "all"
set action deny
set schedule "always"
set service "ALL"
set logtraffic all
next
edit 1
set name "Allow-HTTP"
set srcintf "internal"
set dstintf "wan1"
set srcaddr "10.0.0.0/8"
set dstaddr "all"
set action accept
set schedule "always"
set service "HTTP"
set logtraffic all
next
end
A
The Allow-HTTP policy uses service HTTP but the traffic uses HTTPS
Why wrong: The question states HTTP traffic.
B
The Deny-All policy is placed above the Allow-HTTP policy
Policy ID 0 has lower sequence number and matches first.
C
The Allow-HTTP policy has the wrong source interface
Why wrong: The source interface is correct for internal traffic.
D
The Allow-HTTP policy is disabled
Why wrong: The exhibit shows it is configured, but not necessarily disabled; the issue is order.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The Deny-All policy is placed above the Allow-HTTP policy
In FortiGate firewall policies, the first matching policy is applied to traffic. The Deny-All policy is placed above the Allow-HTTP policy, so traffic from 10.0.0.0/8 to the internet on HTTP matches the Deny-All policy first and is denied before reaching the Allow-HTTP policy. This is a classic policy ordering issue.
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 Allow-HTTP policy uses service HTTP but the traffic uses HTTPS
The Deny-All policy is placed above the Allow-HTTP policy
Why this is correct
Policy ID 0 has lower sequence number and matches first.
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 Allow-HTTP policy has the wrong source interface
Why it's wrong here
The source interface is correct for internal traffic.
✗
The Allow-HTTP policy is disabled
Why it's wrong here
The exhibit shows it is configured, but not necessarily disabled; the issue is order.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume policies are evaluated based on a 'most specific match' logic rather than the actual sequential order, leading them to overlook the policy placement as the root cause.
Trap categories for this question
Command / output trap
The exhibit shows it is configured, but not necessarily disabled; the issue is order.
Detailed technical explanation
How to think about this question
FortiGate firewall policies are evaluated sequentially from top to bottom based on the policy ID order in the GUI or CLI. The first policy that matches the source, destination, service, and interface is applied, and subsequent policies are ignored. This behavior is defined in the FortiOS firewall processing logic and is critical for correctly implementing security rules, especially when mixing explicit allow and catch-all deny policies.
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.
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-All policy is placed above the Allow-HTTP policy — In FortiGate firewall policies, the first matching policy is applied to traffic. The Deny-All policy is placed above the Allow-HTTP policy, so traffic from 10.0.0.0/8 to the internet on HTTP matches the Deny-All policy first and is denied before reaching the Allow-HTTP policy. This is a classic policy ordering issue.
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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