This NSE4 practice question tests your understanding of authentication and vpn. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.
Which authentication server type can be used with FortiGate to authenticate remote VPN users with two-factor authentication using FortiTokens?
POP3
Why wrong: POP3 is an email protocol, not an authentication server.
LDAP
Why wrong: LDAP does not support two-factor authentication natively.
RADIUS
FortiGate can be configured to authenticate users via RADIUS and use FortiToken as the two-factor method.
TACACS+
Why wrong: TACACS+ is not typically used for VPN authentication on FortiGate.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
RADIUS
FortiToken two-factor authentication can be used with local users or with remote authentication servers like RADIUS. However, FortiToken is natively supported by FortiGate local users and can also be used with RADIUS if the FortiGate acts as the RADIUS client forwarding tokens.
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.
POP3
Why it's wrong here
POP3 is an email protocol, not an authentication server.
LDAP
Why it's wrong here
LDAP does not support two-factor authentication natively.
RADIUS
Why this is correct
FortiGate can be configured to authenticate users via RADIUS and use FortiToken as the two-factor method.
Related concept
Authentication checks who the user is.
TACACS+
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 small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
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
Learn the concepts, then practise the questions
Authentication and VPN practice questions
Targeted practice on this topic area only
All NSE4 questions
1,000 questions across all exam domains
Fortinet NSE 4 Network Security Professional NSE4 study guide
Full concept coverage aligned to exam objectives
NSE4 practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Practise NSE4 questions linked to System and Network Administration.
Practise NSE4 questions linked to Firewall Policies and NAT.
Practise NSE4 questions linked to Authentication and VPN.
Practise NSE4 questions linked to Security Profiles.
Practise NSE4 questions linked to High Availability and Diagnostics.
Practise NSE4 questions linked to NSE4 fundamentals.
Practise NSE4 questions linked to NSE4 scenario.
Practise NSE4 questions linked to NSE4 troubleshooting.
Practice this exam
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
FAQ
Authentication and VPN — This question tests Authentication and VPN — Authentication checks who the user is..
The correct answer is: RADIUS — FortiToken two-factor authentication can be used with local users or with remote authentication servers like RADIUS. However, FortiToken is natively supported by FortiGate local users and can also be used with RADIUS if the FortiGate acts as the RADIUS client forwarding tokens.
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.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
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.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.