- A
Run 'diagnose debug enable' and then reproduce the issue
Why wrong: Debug flow already provides the needed information; additional debug enable is not necessary for identifying the policy.
- B
Use 'diagnose sys session list' to find the policy ID
Why wrong: Session list shows active sessions, not denied sessions.
- C
Review the policy list and look for the policy ID shown in the debug output
The debug flow output typically includes the policy ID that applied. The admin can then review that specific policy.
- D
Check the traffic log for the session to see the policy ID
Traffic logs record the policy ID that processed the session, including denies.
- E
Disable all firewall policies temporarily
Why wrong: This would cause a security risk and is not a targeted troubleshooting step.
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 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.)
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Review the policy list and look for the policy ID shown in the debug output
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.
Key principle: ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Run 'diagnose debug enable' and then reproduce the issue
Why it's wrong here
Debug flow already provides the needed information; additional debug enable is not necessary for identifying the policy.
- ✗
Use 'diagnose sys session list' to find the policy ID
Why it's wrong here
Session list shows active sessions, not denied sessions.
- ✓
Review the policy list and look for the policy ID shown in the debug output
Why this is correct
The debug flow output typically includes the policy ID that applied. The admin can then review that specific policy.
Related concept
Standard ACLs match source addresses.
- ✓
Check the traffic log for the session to see the policy ID
Why this is correct
Traffic logs record the policy ID that processed the session, including denies.
Related concept
Standard ACLs match source addresses.
- ✗
Disable all firewall policies temporarily
Why it's wrong here
This would cause a security risk and is not a targeted troubleshooting step.
Common exam traps
Common exam trap: ACLs stop at the first match
ACLs are processed top to bottom. The first matching entry wins, and an implicit deny usually exists at the end.
Trap categories for this question
Command / output trap
Session list shows active sessions, not denied sessions.
Detailed technical explanation
How to think about this question
ACL questions test precision: source, destination, protocol, port and direction. A generally correct ACL can still fail if it is applied on the wrong interface or in the wrong direction.
KKey Concepts to Remember
- Standard ACLs match source addresses.
- Extended ACLs can match source, destination, protocol and ports.
- The first matching ACL entry is used.
- There is usually an implicit deny at the end.
TExam Day Tips
- Check inbound versus outbound direction.
- Read the ACL from top to bottom.
- Look for a broader permit or deny above the intended line.
Key takeaway
ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
Real-world example
How this comes up in practice
A security administrator must allow nursing staff to reach a patient records server while blocking access from the guest Wi-Fi VLAN. After applying an extended ACL, traffic is still blocked from nursing workstations. The ACL was applied outbound instead of inbound on the wrong interface. Questions like this test ACL direction and placement rules.
What to study next
Got this wrong? Here's your next step.
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related NSE4 ACL questions on filtering logic and placement.
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FAQ
Questions learners often ask
What does this NSE4 question test?
High Availability and Diagnostics — This question tests High Availability and Diagnostics — Standard ACLs match source addresses..
What is the correct answer to this question?
The correct answer is: Review the policy list and look for the policy ID shown in the debug output — 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.
What should I do if I get this NSE4 question wrong?
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related NSE4 ACL questions on filtering logic and placement.
What is the key concept behind this question?
Standard ACLs match source addresses.
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Last reviewed: Jun 21, 2026
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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