The answer is to examine the routing table for the destination network. This is correct because even with a permissive policy, the FortiGate must have a valid route to forward traffic; without a route, the packet is dropped before a session is ever created, leaving the session table empty. On the Fortinet NSE 4 exam, this scenario tests your understanding of the packet flow sequence—policy is checked after routing, so a missing or incorrect route is a common root cause when no sessions appear. A frequent trap is assuming a policy alone guarantees traffic flow, but the FortiGate must also know where to send the packet. Memory tip: think "Route before Rule"—if the route is missing, the session never gets a chance to start.
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 is troubleshooting a FortiGate that is not passing traffic. The policy allows traffic, but the session table shows no sessions. Which THREE steps should the administrator take to diagnose the issue? (Choose three.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Verify the interface status and link state.
Option A is correct because if the interface is down or has a link issue, the FortiGate cannot send or receive any traffic, resulting in no sessions being created even if the policy allows traffic. Verifying interface status and link state is a fundamental first step in troubleshooting connectivity issues, as it ensures the physical or logical layer is operational before checking higher-layer configurations.
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.
✓
Verify the interface status and link state.
Why this is correct
Interface down would stop traffic.
Related concept
Read the scenario before looking for a memorised answer.
✗
Run 'diagnose npu np6 show' to check offloading.
Why it's wrong here
This is for NP6 hardware, not general troubleshooting.
✓
Check the ARP table to ensure the next-hop MAC is resolved.
Why this is correct
If ARP is incomplete, traffic cannot be forwarded.
Related concept
Read the scenario before looking for a memorised answer.
✓
Examine the routing table for the destination network.
Why this is correct
Missing route would drop traffic.
Related concept
Read the scenario before looking for a memorised answer.
✗
Disable the firewall policy and check if traffic flows.
Why it's wrong here
Disabling policy reduces security; better to check other causes.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may assume a policy allowing traffic guarantees session creation, but they overlook that the FortiGate must first be able to physically receive and forward the traffic, which depends on interface, ARP, and routing being correctly configured.
Detailed technical explanation
How to think about this question
When a FortiGate fails to create sessions, it often indicates that traffic is not reaching the device or is being dropped before session lookup. The ARP table (Option C) must contain a resolved MAC address for the next-hop gateway; if ARP resolution fails, the FortiGate cannot forward packets, and no sessions are created. The routing table (Option D) must have a valid route to the destination; without a route, the FortiGate drops the packet and does not create a session. These three steps—interface status, ARP resolution, and routing—form the core of Layer 2/3 connectivity verification in FortiOS.
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: Verify the interface status and link state. — Option A is correct because if the interface is down or has a link issue, the FortiGate cannot send or receive any traffic, resulting in no sessions being created even if the policy allows traffic. Verifying interface status and link state is a fundamental first step in troubleshooting connectivity issues, as it ensures the physical or logical layer is operational before checking higher-layer configurations.
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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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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