Quick Answer
The answer is LDAP, as this is the authentication server type that must be configured on a FortiGate to use Active Directory credentials for firewall administrator logins. LDAP, or Lightweight Directory Access Protocol, is the standard protocol for querying and retrieving user information from an Active Directory database, allowing the FortiGate to verify administrator credentials against AD without requiring a separate directory service. On the Fortinet NSE 4 Network Security Professional NSE4 exam, this concept tests your understanding of how FortiGate integrates with external authentication sources; a common trap is confusing LDAP with RADIUS, but remember that LDAP is the native protocol for direct Active Directory queries, while RADIUS is typically used for network access or third-party servers. For the exam, a useful memory tip is "LDAP Looks Directly At People" — LDAP looks directly at Active Directory for user authentication, whereas RADIUS often routes through an intermediary.
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 administrator wants to use Active Directory credentials to authenticate firewall administrators. Which authentication server type should be configured on the FortiGate?
TACACS+
Why wrong: TACACS+ is a Cisco protocol, not typically used with AD.
FSSO
Why wrong: FSSO is a single sign-on method, not an authentication server type.
LDAP
LDAP is the protocol used to query Active Directory for authentication and user attributes.
RADIUS
Why wrong: RADIUS can be used but is not the direct AD protocol; LDAP is the native choice.
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
FortiGate supports LDAP for integration with Active Directory. LDAP is the standard protocol for querying AD user information.
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.
TACACS+
FSSO
Why it's wrong here
FSSO is a single sign-on method, not an authentication server type.
LDAP
Why this is correct
LDAP is the protocol used to query Active Directory for authentication and user attributes.
Related concept
Authentication checks who the user is.
RADIUS
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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Authentication and VPN practice questions
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Related practice questions
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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 — FortiGate supports LDAP for integration with Active Directory. LDAP is the standard protocol for querying AD user information.
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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Same concept, more angles
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 admin wants to authenticate VPN users against an existing Microsoft Active Directory. Which authentication method should be configured on the FortiGate?
easyWhy A: LDAP is the standard protocol for querying Active Directory for user authentication.
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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