The answer is that the firewall policy action is set to DENY. Even when a firewall policy has NAT enabled and a correct default route pointing to the ISP gateway, the policy itself must be configured with an ACCEPT action to permit traffic; a DENY action silently drops all matching packets, which explains why users cannot access external resources despite correct routing and NAT. On the Fortinet NSE 4 Network Security Professional NSE4 exam, this scenario tests your understanding that policy actions override all other configurations—a common trap is to focus solely on NAT or routing issues when troubleshooting internet access, forgetting to verify the fundamental permit/deny toggle. A reliable memory tip is to remember the acronym “P.A.N.D.”: Policy Action must be ACCEPT, NAT must be enabled, and the Default route must exist; if any one is missing, internet access fails.
NSE4 System and Network Administration Practice Question
This NSE4 practice question tests your understanding of system and network administration. 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 creates a firewall policy to allow internal users to access the internet. The source interface is 'internal', destination interface is 'wan1', and NAT is enabled. Users complain that they cannot access external resources. The administrator verifies that the default route points to the ISP gateway. What is the most likely missing configuration?
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 policy action is set to DENY
The most likely missing configuration is that the firewall policy action is set to DENY. Even with correct NAT, routing, and DNS settings, if the policy action is DENY, traffic from the internal interface to the wan1 interface will be dropped. The administrator must ensure the policy action is ACCEPT to permit outbound traffic.
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 DNS server is not configured on the FortiGate
Why it's wrong here
DNS is for name resolution; if users use IPs, DNS is not necessary.
✗
The FortiGate is in transparent mode
Why it's wrong here
Transparent mode still requires policies and routes.
✓
The policy action is set to DENY
Why this is correct
If the policy action is DENY, traffic is blocked despite other correct settings.
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 session helper for FTP is disabled
Why it's wrong here
FTP helper is not required for general web access.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often overlook the policy action and instead focus on routing or NAT issues, assuming that if the default route and NAT are configured, traffic must flow, but the policy action is the gatekeeper that must be set to ACCEPT.
Detailed technical explanation
How to think about this question
In FortiGate, firewall policies are evaluated sequentially; if the policy action is DENY, the FortiGate drops the packet before any NAT or routing processing occurs. Even with a valid default route and NAT enabled, the policy must have action set to ACCEPT to allow traffic. A common real-world scenario is when a policy is created but accidentally left with the default action of DENY, causing connectivity issues that are not resolved by checking routing or NAT.
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.
System and Network Administration — This question tests System and Network Administration — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The policy action is set to DENY — The most likely missing configuration is that the firewall policy action is set to DENY. Even with correct NAT, routing, and DNS settings, if the policy action is DENY, traffic from the internal interface to the wan1 interface will be dropped. The administrator must ensure the policy action is ACCEPT to permit outbound traffic.
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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