Quick Answer

The answer is policy-based routing (PBR) configured within a firewall policy. This feature allows a FortiGate to override the default route for specific traffic by matching criteria like source and destination addresses, then forcing that traffic out a designated interface such as port3. Unlike static routes that rely solely on the destination prefix, PBR enables granular, interface-based path selection, making it the correct tool when you need to route LAN-to-DMZ traffic through a specific port regardless of the routing table. On the Fortinet NSE 4 exam, this scenario tests your understanding of how PBR differs from policy routes applied globally—a common trap is confusing PBR with SD-WAN rules or static routes. Remember that PBR lives inside the firewall policy itself, not the routing table. A helpful memory tip: “Policy first, then path—PBR picks the port before the packet looks up the route.”