NSE 4 – FortiGate 6.4 — Question 115

FortiGate is operating in NAT mode and is configured with two virtual LAN (VLAN) subinterfaces added to the same physical interface.
In this scenario, which statement about VLAN IDs is true?

Answer options

• A. The two VLAN subinterfaces can have the same VLAN ID only if they belong to different VDOMs.
• B. The two VLAN subinterfaces must have different VLAN IDs.
• C. The two VLAN subinterfaces can have the same VLAN ID only if they have IP addresses in the same subnet.
• D. The two VLAN subinterfaces can have the same VLAN ID only if they have IP addresses in different subnets.

Correct answer: B

Explanation

The correct answer is B because each VLAN subinterface must have a unique VLAN ID to avoid conflicts and ensure proper traffic separation. Options A, C, and D suggest scenarios where VLAN IDs can be duplicated, which is incorrect in the context of a single physical interface in NAT mode.