Quick Answer
The answer is an LDAP server. This is the correct choice because LDAP is the standard protocol used to query and authenticate against Microsoft Active Directory; when a FortiGate is configured with an LDAP server object, it can securely validate SSL VPN users by sending their domain credentials directly to the domain controller for verification. On the Fortinet NSE 4 exam, this question tests your understanding of how remote authentication integrates with on-premises identity stores—a common trap is confusing LDAP with RADIUS, but remember that AD natively speaks LDAP, while RADIUS is typically used for third-party or two-factor systems. A helpful memory tip: think of LDAP as the “directory lookup” protocol that reads usernames and passwords from AD, making it the direct path for SSL VPN authentication with domain credentials.
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.
An admin needs to authenticate remote users connecting via SSL VPN. The users are in an Active Directory domain. Which authentication method should be configured on the FortiGate to allow users to log in with their domain credentials?
LDAP server
LDAP is the standard protocol for authenticating against an AD domain.
Local user database
Why wrong: Local users are defined on the FortiGate itself, not AD.
RADIUS server
Why wrong: RADIUS can be used but typically requires additional setup; LDAP is more direct for AD.
FSSO
Why wrong: FSSO provides transparent authentication based on Windows login but is not the direct authentication for SSL VPN login.
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 server
LDAP is the protocol used to authenticate against Active Directory. FortiGate can query AD via LDAP to validate user credentials.
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.
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 server — LDAP is the protocol used to authenticate against Active Directory. FortiGate can query AD via LDAP to validate user credentials.
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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