The answer is to create a firewall policy with the source interface set to 'guest', destination 'any', and action 'ACCEPT', then enable 'Authentication' with the 'Captive Portal' option. This configuration is correct because captive portal firewall policy configuration relies on the FortiGate intercepting traffic from unauthenticated users on the specified interface; when the policy matches, the FortiGate redirects HTTP requests to the captive portal login page instead of forwarding the traffic. On the Fortinet NSE 4 Network Security Professional NSE4 exam, this scenario tests your understanding that captive portal is enforced at the firewall policy level—not just on the interface—and a common trap is choosing a 'DENY' action, which blocks all traffic without redirecting. Remember the key distinction: the policy must ACCEPT the traffic to trigger the authentication challenge, not deny it. A useful memory tip is "ACCEPT to redirect, DENY to reject"—if you deny, users never see the portal.
NSE4 Authentication and VPN Practice Question
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 company wants to use captive portal authentication on a guest Wi-Fi network. The FortiGate is connected to the switchport of the access point. Which firewall configuration is required to redirect unauthenticated users to the captive portal?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Create a policy with source interface 'guest', destination 'any', and action 'ACCEPT' with 'Authentication' set to 'Captive Portal'.
Captive portal works by configuring a firewall policy that matches the user's traffic with 'Authentication' set to 'Captive Portal' or by enabling it directly on the interface. Typically, a policy with 'Security Mode' 'Captive Portal' forces redirect.
Key principle: A trunk being up does not mean the VLAN is allowed across it. Always verify the allowed VLAN list and whether the VLAN exists on both switches.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Set the 'Guest Management' feature in the FortiGate dashboard.
Why it's wrong here
Guest management is separate; it uses captive portal but requires a policy to trigger it.
✓
Create a policy with source interface 'guest', destination 'any', and action 'ACCEPT' with 'Authentication' set to 'Captive Portal'.
Why this is correct
This policy catches unauthenticated traffic and redirects to the captive portal.
Related concept
Access ports place end devices into a single VLAN.
✗
Configure a 'Landing Page' under SSL-VPN settings.
Enable 'Captive Portal' on the interface under System > Network > Interface.
Why it's wrong here
Captive portal is not enabled on the interface directly; it's done via policies or security profiles.
Common exam traps
Common exam trap: an active trunk can still block the VLAN you need
A trunk being up does not prove every VLAN is crossing it. Check allowed VLAN lists, native VLAN mismatch, VLAN existence and access-port assignment.
Detailed technical explanation
How to think about this question
VLAN questions usually combine access-port and trunking clues. The key is to identify whether the issue is local to one switchport, caused by the trunk, or caused by the VLAN not existing where it needs to exist.
KKey Concepts to Remember
Access ports place end devices into a single VLAN.
Trunk ports carry multiple VLANs between switches.
Allowed VLAN lists decide which VLANs can cross a trunk.
Native VLAN mismatch can create confusing symptoms.
TExam Day Tips
→Use show vlan brief to verify access VLANs.
→Use show interfaces trunk to verify trunk state and allowed VLANs.
→Do not treat every same-VLAN issue as a routing problem.
Key takeaway
A trunk being up does not mean the VLAN is allowed across it. Always verify the allowed VLAN list and whether the VLAN exists on both switches.
Real-world example
How this comes up in practice
A help-desk technician troubleshoots why a newly connected PC cannot reach shared printers on the same floor. The cable is good, the switch port is active, but the PC is in VLAN 20 and the printers are in VLAN 10. The uplink trunk only allows VLAN 10. A trunk being up does not mean every VLAN crosses it.
What to study next
Got this wrong? Here's your next step.
Review VLAN allowed lists, native VLAN mismatch detection, and how to verify VLAN membership with show vlan brief and show interfaces trunk. Then practise related NSE4 questions on switching, trunking, and access-port configuration.
Authentication and VPN — This question tests Authentication and VPN — Access ports place end devices into a single VLAN..
What is the correct answer to this question?
The correct answer is: Create a policy with source interface 'guest', destination 'any', and action 'ACCEPT' with 'Authentication' set to 'Captive Portal'. — Captive portal works by configuring a firewall policy that matches the user's traffic with 'Authentication' set to 'Captive Portal' or by enabling it directly on the interface. Typically, a policy with 'Security Mode' 'Captive Portal' forces redirect.
What should I do if I get this NSE4 question wrong?
Review VLAN allowed lists, native VLAN mismatch detection, and how to verify VLAN membership with show vlan brief and show interfaces trunk. Then practise related NSE4 questions on switching, trunking, and access-port configuration.
What is the key concept behind this question?
Access ports place end devices into a single VLAN.
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