Refer to the exhibit.

The correct answer is D . In a Layer 3 registration or isolation network design, DHCP requests from the isolated registration VLAN are not served locally on that VLAN by a normal production DHCP server. Instead, the registration VLAN’s DHCP relay must forward DHCP traffic to FortiNAC-F port2 , because port2 is the captive network service interface. The study guide states that in Layer 3 captive networks, DHCP traffic is relayed to port2 from the captive networks, and that the FortiNAC-F port2 interface provides DHCP, DNS, and captive portal services for hosts assigned to those captive networks.

In the exhibit, the registration VLAN is 192.168.10.x/24 , with gateway 192.168.10.254 . That gateway is where the DHCP relay would be configured, but it is not the relay destination. The relay destination must be the FortiNAC-F port2 address, shown as 192.168.200.10 . The corporate DHCP server 192.168.100.75 is for production network addressing, not registration isolation. The FortiNAC-F port1 address 192.168.100.20 is the administrative or production-facing interface, not the captive network service interface. Therefore, the DHCP relay should point to 192.168.200.10 .