Anything but the "different VLAN" answer is impossible from a networking view, as well as configuration on the FG is concerned. At least up to 7.0 it's impossible to configure the same VLAN on the same physical link multiple times, no matter if it's in separate VDOMs or not.

I used my own lab to resolve this question: If you use the same VLAN ID to add a second subinterface to the same physical interface is not allowed you get the error ( VLAN ID used by another VLAN switch) unless you change the VLAN Protocol to 802.1AD, no matter the VDOM you assign the subinterface. Being said that, options A and B are not true, the option C is correct and option D is true if as I said before you use 802.1Q in one subinterface and 802.1AD in the second subinterface.

C and D

Anybody got in Exam newly? Are those questions legit still?

C is correct but not sure about the other, this questions seems like wrong to me it has single answer only

c,D In a scenario where FortiGate is operating in NAT mode and configured with two virtual LAN (VLAN) subinterfaces added to the same physical interface, the correct requirements for the VLAN ID are: C. **The two VLAN subinterfaces must have different VLAN IDs.** Each VLAN subinterface should have a unique VLAN ID to properly segregate traffic between VLANs. D. **The two VLAN subinterfaces can have the same VLAN ID, only if they have IP addresses in different subnets.** If two VLAN subinterfaces share the same VLAN ID, they must belong to different IP subnets to avoid IP address conflicts and ensure proper routing of traffic. So, options C and D are the correct requirements for the VLAN ID in this scenario.

Las correctas son la B y C

Las correctas con B y C

Tested in lab, vdom is not significant. Only option is to use 802.1Q and 802.1AD with different subnet

C is definitely true as everyone has already mentioned. B and D are also true if you change one of the interfaces to use 802.1AD.

Correct

B & C is the correct answer

This Question has been asked on 7.0 and 6.4 NSE 4. It’s always been a one answer question. So it’s only C.

Basic concept of VLAN.

VLANs split your physical LAN into multiple, logical LANs. In NAT operation mode, each VLAN forms a separate broadcast domain. Multiple VLANs can coexist in the same physical interface, provided they have different VLAN IDs. In this way, a physical interface is split into two or more logical interfaces. A tag is added to each Ethernet frame to identify the VLAN to which it belongs. Note that in a multi-VDOM environment, the physical interface and its VLAN sub-interface can be in separate VDOMs.

b and c

b and c