This NSE4 practice question tests your understanding of firewall policies and nat. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 configures a VIP for port forwarding: public IP 203.0.113.10 port 8080 to internal server 10.0.1.10 port 80. External users can connect to http://203.0.113.10:8080 but receive a timeout. The firewall policy allows traffic from any to the VIP on destination port 8080. The internal server is reachable from internal hosts. What is the most likely problem?
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 destination service is set to HTTP (port 80) instead of port 8080
Option C is correct because the firewall policy must match the destination port of the incoming traffic. External users connect to port 8080 on the VIP, but if the policy's destination service is set to HTTP (port 80), the policy will not match traffic destined for port 8080. Even though the VIP translates the destination to port 80 on the internal server, the firewall policy evaluation occurs before NAT translation, so the policy must match the original destination port (8080).
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 internal server is not running a web server
Why it's wrong here
It is reachable from internal hosts.
✗
The VIP is not associated with the policy
Why it's wrong here
The policy uses the VIP as destination address.
✓
The policy destination service is set to HTTP (port 80) instead of port 8080
Why this is correct
Before translation, the destination port is 8080; policy must match pre-NAT port.
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 trap: answer the scenario, not the keyword
The trap here is that candidates mistakenly think the policy should match the internal server's port (80) because the VIP translates to that port, but FortiOS policy evaluation occurs before NAT, so the policy must match the original destination port (8080).
Detailed technical explanation
How to think about this question
In FortiOS, firewall policies are evaluated before NAT translation. The policy must match the original packet's destination IP and port (the VIP's public IP and port), not the translated values. The VIP object defines the mapping, but the policy's destination service must reflect the incoming port (8080), not the internal server's port (80). A common real-world scenario is when an administrator configures a VIP to translate port 8080 to port 80 but forgets to update the policy service, causing traffic to be dropped at the policy layer.
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.
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 policy destination service is set to HTTP (port 80) instead of port 8080 — Option C is correct because the firewall policy must match the destination port of the incoming traffic. External users connect to port 8080 on the VIP, but if the policy's destination service is set to HTTP (port 80), the policy will not match traffic destined for port 8080. Even though the VIP translates the destination to port 80 on the internal server, the firewall policy evaluation occurs before NAT translation, so the policy must match the original destination port (8080).
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
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
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
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.