In a FortiNAC-F deployment, the configuration of theDHCP scopefor isolation networks (Registration, Remediation, etc.) must perfectly align with the underlying network infrastructure to ensure that isolated hosts can communicate with the FortiNAC appliance. In the provided exhibits, there is a clear discrepancy between theDHCP configurationand theNetwork Topology.

As shown in the " Network Topology " exhibit, theRegistration Networkresides on a router interface (or sub-interface) with the IP address192.168.180.1. This address represents the default gateway for any host placed into the Registration VLAN. However, the " DHCP configuration " exhibit shows the scope " REG-ScopeOne " configured with aGateway of 10.0.1.254. This 10.0.1.254 address belongs to the management/service network (port2 of FortiNAC), not the registration subnet. If a host in the Registration VLAN receives this incorrect gateway via DHCP, it will attempt to send all off-link traffic to an unreachable IP, preventing it from loading theCaptive Portalor communicating with the FortiNAC server.

According to theFortiNAC-F Configuration Wizard Reference, when defining a Layer 3 network scope, the " Gateway " field must contain the IP address of the router interface that acts as the gateway for that specific isolation VLAN. The FortiNAC appliance itself usually sits on a different subnet, and traffic is directed to it via the router ' s DHCP Relay (IP Helper) and DNS redirection.

" When configuring scopes for a Layer 3 network, theGatewayvalue must be the IP address of the router interface for that subnet. This allows the host to reach its local gateway to route traffic. If the gateway is misconfigured, the host will be unable to reach the FortiNAC eth1/port2 interface for registration... Ensure the Gateway matches the network topology for the isolation VLAN. " —FortiNAC-F Configuration Wizard Reference Manual: DHCP Scopes.

The correct answers are C, D, and E . In a Layer 3 captive or isolation network design, FortiNAC-F port2 acts as the captive network service interface. The study guide states that Layer 3 captive networks require DHCP traffic to be relayed to port2 from the captive networks, and that the FortiNAC-F interface provides DHCP, DNS, and captive portal services to hosts assigned to any captive network.

That means the firewall path between the isolation VLANs and FortiNAC-F must allow DHCP , so isolated endpoints can receive an IP address from the FortiNAC-F captive network scope; DNS , so the isolated endpoint uses FortiNAC-F as its DNS server and gets redirected correctly; and HTTP/HTTPS , so the endpoint can load the FortiNAC-F captive portal page. The guide’s browser-redirection flow confirms this sequence: the host is moved to the isolation VLAN, requests DHCP, receives FortiNAC-F as the DNS server, performs DNS lookup, and then Apache/Tomcat services present the portal content.

Option A , DDNS, is not required for captive portal operation. Option B , NTP, may be useful for endpoint time accuracy or certificate-related workflows, but it is not part of the minimum traffic required for FortiNAC-F isolation network operation.

In FortiNAC-F, theLayer 3 Network typeis specifically designed for deployments where the isolation networks—such as Registration, Remediation, and Dead End—are separated from the FortiNAC appliance ' s service interface (port2) by one or more routers. This architecture is common in large, distributed enterprise environments where endpoints in different physical locations or branches must be isolated into subnets that are local to their respective network equipment.

The reason the Configuration Wizard allows for more than one DHCP scope for a single isolation network type (state) is thatthere can be more than one isolation network of each typeacross the infrastructure. For instance, if an organization has three different sites, each site might require its own unique Layer 3 registration subnet to ensure efficient routing and to accommodate local IP address management. By allowing multiple scopes for the " Registration " state, FortiNAC can provide the appropriate IP address, gateway, and DNS settings to a rogue host regardless of which site ' s registration VLAN it is placed into.

When an endpoint is isolated, the network infrastructure (via DHCP Relay/IP Helper) directs the DHCP request to the FortiNAC service interface. FortiNAC then identifies which scope to use based on the incoming request ' s gateway information. This flexibility ensures that the system is not limited to a single flat subnet for each isolation state, supporting a scalable, multi-routed network topology.

" Multiple scopes are allowed for each isolation state (Registration, Remediation, Dead End, VPN, Authentication, Isolation, and Access Point Management). Within these scopes, multiple ranges in the lease pool are also permitted... This configWizard option is used when Isolation Networks are separated from the FortiNAC Appliance ' s port2 interface by a router. " —FortiNAC-F Configuration Wizard Reference Manual: Layer 3 Network Section.