According to the SD-WAN 7.6 Core Administrator curriculum and the diagnostic outputs shown in the exhibit, the reason traffic is steered to HUB1-VPN3 instead of the expected HUB1-VPN1 (defined in SD-WAN rule ID 1) can be explained by two core routing principles in FortiOS:

Valid Route Requirement (Option A): In the diagnose sys sdwan service 4 output (which corresponds to Rule ID 1), it shows the rule has members HUB1-VPN1, HUB1-VPN2, and HUB1-VPN3. A key principle of SD-WAN steering is that for a member to be " selectable " by a rule, it must have a valid route to the destination in the routing table (RIB/FIB). If the routing table output (the third section of the exhibit) shows a route to 10.0.0.0/8 via HUB1-VPN3 but not through HUB1-VPN1, the SD-WAN engine will skip HUB1-VPN1 entirely because it is considered a " non-reachable " path for that specific destination.

Policy Route Precedence (Option D): In the FortiOS route lookup hierarchy, Regular Policy Routes (PBR) are evaluated before SD-WAN rules. If an administrator has configured a traditional Policy Route (found under Network > Policy Routes) that matches traffic destined for 10.0.0.0/8 and specifies HUB1-VPN3 as the outgoing interface, the FortiGate will forward the packet based on that policy route and will never evaluate the SD-WAN rules for that session. This " bypass " occurs regardless of whether the SD-WAN rule would have chosen a " better " link.

Why other options are incorrect:

Option B: While member configuration priority (cfg_order) is a tie-breaker in some strategies, the SD-WAN rule logic is only applied if the routing table allows it or if a higher-priority policy route doesn ' t intercept the traffic first.

Option C: Lower route priority (which means higher preference in the RIB) affects the Implicit Rule (standard routing). However, SD-WAN rules are designed to override RIB priority for matching traffic. If HUB1-VPN1 was a valid candidate and no Policy Route existed, the SD-WAN rule would typically ignore RIB priority to enforce its own steering strategy.