The answer is that the firewall policy only allows HTTP (port 80), but users are trying to access HTTPS (port 443). This is the most likely cause because modern websites almost universally redirect HTTP traffic to HTTPS or require a secure connection, meaning the FortiGate drops the HTTPS packets since no policy explicitly permits TCP port 443. On the Fortinet NSE 4 Network Security Professional NSE4 exam, this scenario tests your understanding of how service objects map to specific ports and the default implicit deny behavior—a common trap is assuming "HTTP" covers all web traffic. Remember that when troubleshooting a FortiGate policy that allows HTTP but users can't browse, always check whether the service includes HTTPS, as most sites now enforce encryption. A quick memory tip: "HTTP is for reading, HTTPS is for securing—if your policy only has one, users are done."
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 FortiGate administrator configures a firewall policy to allow HTTP traffic from internal users to the internet. The policy uses source address 'internal_subnet', destination address 'all', and service 'HTTP'. After applying the policy, users report they cannot access websites. What is the most likely cause?
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 only allows HTTP (port 80), but users are likely accessing HTTPS (port 443)
The policy explicitly allows HTTP (TCP port 80), but modern web traffic predominantly uses HTTPS (TCP port 443). Since the service object does not include HTTPS, the firewall will drop HTTPS packets by default unless a separate policy or rule permits them. This is the most likely reason users cannot access websites, as most sites redirect HTTP to HTTPS or require HTTPS for secure connections.
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 source interface is misconfigured
Why it's wrong here
No indication of interface misconfiguration.
✗
The destination address object 'all' is incorrect
Why it's wrong here
'all' is a valid default address object.
✗
The policy order is incorrect and a deny policy above is blocking the traffic
Why it's wrong here
The scenario does not mention any deny policies. Order is not the issue.
✓
The policy only allows HTTP (port 80), but users are likely accessing HTTPS (port 443)
Why this is correct
A common oversight: the policy only permits port 80, but most websites use HTTPS on port 443.
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 traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume 'HTTP' covers all web traffic, but FortiGate treats HTTP and HTTPS as distinct services based on port numbers, and the implicit deny will block any unmatched traffic.
Trap categories for this question
Scenario analysis trap
The scenario does not mention any deny policies. Order is not the issue.
Detailed technical explanation
How to think about this question
FortiGate firewall policies match traffic based on source/destination interfaces, addresses, and services. The service object 'HTTP' is predefined for TCP port 80, while 'HTTPS' is a separate object for TCP port 443. When a user types a URL, modern browsers default to HTTPS, so the firewall sees a destination port 443 packet, which does not match the HTTP service, and the implicit deny rule at the end of the policy list drops it. Administrators must either add a separate policy for HTTPS or use a service group that includes both ports.
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 only allows HTTP (port 80), but users are likely accessing HTTPS (port 443) — The policy explicitly allows HTTP (TCP port 80), but modern web traffic predominantly uses HTTPS (TCP port 443). Since the service object does not include HTTPS, the firewall will drop HTTPS packets by default unless a separate policy or rule permits them. This is the most likely reason users cannot access websites, as most sites redirect HTTP to HTTPS or require HTTPS for secure connections.
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 →
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A network administrator configures a firewall policy to allow HTTP traffic from the internal network (10.0.0.0/8) to a web server (172.16.1.10). Users on the 10.0.0.0/8 network cannot access the web server, but other internal users can. The administrator checks the policy list and sees the policy is enabled and in the correct position. What is the most likely cause?
medium
A.The policy is placed below a deny-all policy
B.NAT is not configured on the policy
✓ C.The firewall does not have a route to the 10.0.0.0/8 network
D.The policy is disabled
Why C: The most likely cause is that the firewall does not have a route to the 10.0.0.0/8 network. Even though the policy is enabled and correctly positioned, the firewall must have a return route to the source network (10.0.0.0/8) for the web server's response traffic to reach the users. Without this route, the firewall drops the return packets, causing connectivity failure for those specific users.
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.