The answer is the diagnose debug flow and diagnose sys session filter commands. These two tools allow an administrator to verify traffic hitting the correct firewall policy by tracing the packet’s path through the policy lookup process or by inspecting active session entries for a specific source IP. The diagnose debug flow command provides a real-time, step-by-step trace of how a packet is processed, including which policy it matches, while diagnose sys session filter src 10.0.0.1 displays existing sessions filtered by source, confirming that traffic is indeed being handled by the expected policy. On the Fortinet NSE 4 Network Security Professional NSE4 exam, this question tests your ability to differentiate between diagnostic tools—many candidates mistakenly choose the packet sniffer (diagnose sniffer packet), which captures raw packets but does not reveal policy matching. A common trap is assuming that logging alone confirms policy hits; you must use these debug commands to verify. Memory tip: think “Flow for the path, Filter for the fact”—debug flow shows the journey, session filter shows the result.
NSE4 High Availability and Diagnostics Practice Question
This NSE4 practice question tests your understanding of high availability and diagnostics. 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 is troubleshooting why traffic from a specific source IP is not being logged. The traffic is allowed by a firewall policy with logging enabled. Which TWO commands could the administrator use to verify if the traffic is hitting the expected policy? (Choose two.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
diagnose debug flow
Diagnose debug flow traces traffic through the policy lookup. Diagnose sys session filter can show active sessions for that source IP. Sniffer packet captures packets but doesn't directly show policy match.
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.
✗
get system performance status
Why it's wrong here
Shows system status, not traffic flow.
✓
diagnose debug flow
Why this is correct
Shows policy matching in real-time.
Related concept
Read the scenario before looking for a memorised answer.
✗
diagnose sniffer packet any 'host 10.0.0.1'
Why it's wrong here
Packet capture shows packets but not which policy they match.
✓
diagnose sys session filter src 10.0.0.1
Why this is correct
Filters sessions by source IP; then 'diagnose sys session list' shows the session and policy ID.
Related concept
Read the scenario before looking for a memorised answer.
✗
diagnose debug application fnbamd
Why it's wrong here
This debugs authentication daemon, not traffic flow.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Trap categories for this question
Command / output trap
Shows system status, not traffic flow.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
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.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→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 practitioner preparing for the NSE4 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Got this wrong? Here's your next step.
Identify which NSE4 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
High Availability and Diagnostics — This question tests High Availability and Diagnostics — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: diagnose debug flow — Diagnose debug flow traces traffic through the policy lookup. Diagnose sys session filter can show active sessions for that source IP. Sniffer packet captures packets but doesn't directly show policy match.
What should I do if I get this NSE4 question wrong?
Identify which NSE4 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
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 FortiGate administrator is troubleshooting a traffic issue where users cannot access a specific website. The administrator runs 'diagnose debug flow' and sees the output indicating that traffic is being denied by a firewall policy. Which two actions should the administrator take to identify the specific policy denying the traffic? (Choose two.)
medium
A.Run 'diagnose debug enable' and then reproduce the issue
B.Use 'diagnose sys session list' to find the policy ID
✓ C.Review the policy list and look for the policy ID shown in the debug output
✓ D.Check the traffic log for the session to see the policy ID
E.Disable all firewall policies temporarily
Why C: The debug flow output includes the policy ID that denied the traffic. The administrator can check the policy details using 'show firewall policy <id>' or check the traffic log for the session to see which policy was matched.
Last reviewed: Jun 21, 2026
Question Discussion
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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.
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