Fortinet NSE6_SDW_AD-7.6 Exam Dumps

For FortiGate to steer traffic using SD-WAN rules, two foundational elements must be in place: available WAN paths (underlay links) and firewall policies that allow traffic to reach the SD-WAN interface.

Underlay links (Option B) are mandatory because SD-WAN operates by selecting among multiple WAN transports (for example, broadband, MPLS, LTE, or IPsec tunnels). These links are configured as SD-WAN members and form the physical or logical paths over which traffic can be steered. Without underlay links, SD-WAN has no paths to evaluate or select.

Firewall policies (Option E) are also mandatory because FortiGate only processes and forwards traffic that is explicitly permitted by a firewall policy. When SD-WAN is enabled, firewall policies must reference the SD-WAN interface or SD-WAN zone as the outgoing interface. If no such policy exists, traffic will not be forwarded and SD-WAN rules will never be evaluated.

Why the other options are incorrect:

Security profiles (Option A) are optional and relate to inspection, not SD-WAN steering.

Overlay links (Option C) are used in specific designs such as ADVPN or hub-and-spoke overlays, but SD-WAN can steer traffic without overlays (for example, DIA-only designs).

Traffic shaping (Option D) is not required for SD-WAN decision-making; it is an optional optimization feature.

Therefore, the two required features that must be configured before FortiGate can steer traffic according to SD-WAN rules are underlay links and firewall policies, which correspond to B and E.

The rule is in priority mode with HUB1-VPN1 (seq 4) as the first preferred member, HUB1-VPN2 second, and HUB1-VPN3 third. Latency itself does not cause HUB1-VPN3 to become preferred unless a higher-priority member fails SLA. If HUB1-VPN1's latency exceeds the SLA threshold (here simulated by latency reaching 200 ms), FortiGate stops using it and moves down the priority list. That is when HUB1-VPN3 could become the active path.

In FortiOS (including FortiOS 7.6), FortiGate follows a strict and well-defined route lookup order when determining how to forward traffic. This order is critical for understanding SD-WAN behavior and is explicitly referenced in the FCSS SD-WAN curriculum.

The correct lookup sequence is:

Policy routes (Policy-Based Routing)

Policy routes are evaluated first. If traffic matches a policy route, FortiGate immediately forwards the traffic according to that policy and bypasses all other routing mechanisms.

Internet Service Database (ISDB) routes

If no policy route matches, FortiGate checks ISDB routes. These routes match traffic based on Internet Services rather than destination IP prefixes.

SD-WAN rules

If neither a policy route nor an ISDB route matches, FortiGate evaluates SD-WAN rules to determine the outgoing interface based on the configured SD-WAN strategy.

Routing table (connected, static, and dynamic routes such as BGP)

If no SD-WAN rule matches, FortiGate performs a normal routing table lookup.

FIB (Forwarding Information Base)

The FIB is used to forward the packet based on the selected route.

Drop

If no valid route exists, the packet is dropped.

Among the options provided, only Option D correctly reflects the beginning of this sequence by placing policy routes first, followed by ISDB routes, then SD-WAN rules, and finally static routes (representing the routing table).

Therefore, the correct answer is D.