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 admin wants to authenticate VPN users against an existing Microsoft Active Directory. Which authentication method should be configured on the FortiGate?
LDAP
LDAP is designed for directory services like Active Directory.
RADIUS
Why wrong: RADIUS is a different protocol; while it can be used, LDAP is the direct method for AD.
FSSO
Why wrong: FSSO is used for single sign-on, not direct authentication.
TACACS+
Why wrong: TACACS+ is primarily used for device administration, not user authentication.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
LDAP
LDAP is the standard protocol for querying Active Directory for user authentication.
Key principle: Authentication proves identity; authorization controls what that identity can do after login. Both must work for full privileged access.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
LDAP
Why this is correct
LDAP is designed for directory services like Active Directory.
Related concept
Authentication checks who the user is.
RADIUS
FSSO
Why it's wrong here
FSSO is used for single sign-on, not direct authentication.
TACACS+
Why it's wrong here
TACACS+ is primarily used for device administration, not user authentication.
Common exam traps
Logging in proves the user can authenticate. It does not automatically mean the user is allowed to enter privileged or configuration mode. Watch for AAA authorization, privilege level and command authorization details.
Detailed technical explanation
This kind of question is testing the difference between identity and permission. A user may successfully log in to a router because authentication is working, but still fail to enter configuration mode because authorization is missing, misconfigured or mapped to a lower privilege level.
Key takeaway
Authentication proves identity; authorization controls what that identity can do after login. Both must work for full privileged access.
Real-world example
A junior network technician can log in to a core router but cannot reach the enable prompt or configuration mode. The AAA server is authenticating the login — but the authorisation policy only grants privilege level 1, not 15. Authentication (who you are) is working; authorisation (what you can do) is not.
What to study next
Review Cisco AAA concepts — authentication, authorization, and accounting. Study privilege levels (0–15), command authorization under TACACS+, and how RADIUS differs. Then practise related NSE4 questions on access control and AAA configuration.
Authentication and VPN — study guide chapter
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FAQ
Authentication and VPN — This question tests Authentication and VPN — Authentication checks who the user is..
The correct answer is: LDAP — LDAP is the standard protocol for querying Active Directory for user authentication.
Review Cisco AAA concepts — authentication, authorization, and accounting. Study privilege levels (0–15), command authorization under TACACS+, and how RADIUS differs. Then practise related NSE4 questions on access control and AAA configuration.
Authentication checks who the user is.
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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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