The answer is three possible causes: the FortiGate is not polling the domain controllers correctly, the logon event is not being sent to the FortiGate, and there is a stale IP mapping in the FSSO database. These causes all stem from the core FSSO mechanism, which relies on the FortiGate polling domain controllers for user logon events or receiving those events via a collector agent. If polling fails, events are missed, or the IP-to-user mapping becomes outdated, the FortiGate cannot associate a user’s traffic with their domain credentials, forcing an authentication prompt. On the Fortinet NSE 4 exam, this question tests your understanding of FSSO troubleshooting, often appearing as a multi-select trap where options like FortiToken or captive portal settings distract from the real polling and event-flow issues. A common memory tip is to think of the three “P’s”: Polling, Packet (logon event), and Persistence (stale IP mapping).
NSE4 Authentication and VPN Practice Question
This NSE4 practice question tests your understanding of authentication and vpn. 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.
A FortiGate is configured with FSSO and Active Directory polling. Users report that they are frequently prompted for authentication even though they are logged into the domain. Which THREE possible causes should the administrator investigate?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The user's IP address has changed and the FortiGate still has a stale mapping
Polling issues (A), logon event not sent (B), and stale IP mapping (C) are common causes. Option D is about FortiToken, which is not relevant to FSSO. Option E is for captive portal, not FSSO.
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 user's IP address has changed and the FortiGate still has a stale mapping
Why this is correct
IP changes can cause loss of FSSO session.
Related concept
Read the scenario before looking for a memorised answer.
✗
The FortiToken server is overloaded
Why it's wrong here
FortiToken is not used in FSSO.
✓
The user's workstation is not sending logon events to the domain controller
Why this is correct
If events are not recorded, FortiGate won't see the logon.
Related concept
Read the scenario before looking for a memorised answer.
✗
The captive portal is enabled on the policy
Why it's wrong here
Captive portal would prompt for credentials, but that's a different feature.
✓
The FortiGate is not polling the domain controllers correctly
Why this is correct
Polling must be functional to detect logons.
Related concept
Read the scenario before looking for a memorised answer.
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.
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.
Authentication and VPN — This question tests Authentication and VPN — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The user's IP address has changed and the FortiGate still has a stale mapping — Polling issues (A), logon event not sent (B), and stale IP mapping (C) are common causes. Option D is about FortiToken, which is not relevant to FSSO. Option E is for captive portal, not FSSO.
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.
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Question Discussion
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