NSE4 Authentication and VPN Practice Question
A company wants to provide remote access to internal resources for employees using laptops that may connect from untrusted networks. The security team requires that all traffic between the remote users and the corporate network be encrypted, and that users must authenticate using a username/password plus a one-time passcode from a hardware token. Which FortiGate VPN solution best meets these requirements?
⚠ Common exam trap
Many exam-takers assume any VPN with encryption (like IPsec or L2TP/IPsec) automatically supports two-factor authentication, but FortiGate requires explicit configuration of a second factor like FortiToken, and SSL VPN is the typical solution for this requirement in the NSE4 exam context.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
SSL VPN with FortiToken two-factor authentication
SSL VPN with FortiToken two-factor authentication meets the requirement for encrypted remote access with username/password plus a one-time passcode from a hardware token. SSL VPN provides encrypted tunnels over HTTPS, and FortiToken adds the required second factor, ensuring strong authentication even from untrusted networks.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
IPsec VPN with certificate-based authentication
Why it's wrong here
IPsec VPN with certificate-based authentication uses a digital certificate as the single authentication factor. While certificates strongly verify the device or user identity through PKI, they do not add a second factor such as a one-time code or hardware token. If an endpoint is compromised or a private key is stolen, an attacker can gain access without additional credentials, so this option fails the two-factor requirement.
- ✗
SSL VPN with local password authentication
Why it's wrong here
SSL VPN with local password authentication relies solely on a static password stored in the FortiGate local user database. This is single-factor authentication and is vulnerable to credential theft, brute-force attacks, or password reuse. Because there is no hardware token or one-time password, this option does not meet the company's requirement for two-factor authentication.
- ✓
SSL VPN with FortiToken two-factor authentication
Why this is correct
SSL VPN with FortiToken two-factor authentication correctly combines HTTPS-based encrypted remote access with a time-based one-time password (TOTP) generated by FortiToken. This provides two distinct factors: something the user knows (password) and something the user has (FortiToken device or mobile app). FortiGate can enforce this at the firewall policy level, ensuring both factors are verified before tunnel establishment.
- ✗
L2TP/IPsec VPN with a pre-shared key and user password
Why it's wrong here
L2TP/IPsec with a pre-shared key and user password uses two static secrets rather than two-factor authentication. The pre-shared key is a shared secret between endpoints, not a per-user second factor, and the password is another knowledge factor. This setup does not include a hardware token or one-time code, so it fails to provide the required two-factor authentication.
Quick reference
VPN Protocol Comparison
| Protocol | Port | Encryption | Authentication | Use Case |
|---|---|---|---|---|
| IKEv2 / IPsec | UDP 500 / 4500 | AES-256 | Certificates / PSK | Site-to-site & remote access |
| SSL / TLS VPN | TCP 443 | TLS 1.3 | Certificates / MFA | Clientless remote access |
| L2TP / IPsec | UDP 1701 | AES (IPsec) | PSK / Certificates | Legacy remote access |
| WireGuard | UDP 51820 | ChaCha20 | Public keys | Modern high-performance VPN |
| PPTP | TCP 1723 | MPPE (weak) | MS-CHAPv2 | Legacy — avoid in production |
PPTP is considered insecure. IKEv2/IPsec and SSL VPN are the current recommended options.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.