NSE6_SDW_AD-7.6 Exam Dumps - Fortinet Network Security Expert Questions and Answers

In FortiOS 7.6, when a Performance SLA probe mode is set to Prefer Passive , FortiGate attempts to measure link performance using passive monitoring first , based on real user traffic. Only when passive monitoring is not possible does FortiGate temporarily fall back to active probing.

With Prefer Passive , FortiGate passively monitors TCP traffic flowing through the SD-WAN member to calculate SLA metrics such as latency, jitter, and packet loss. This behavior directly matches option A .

During passive monitoring , FortiGate relies on observed traffic to infer link health. Because no synthetic probes are sent, a completely dead link (with no traffic passing) cannot be detected by the SLA during passive mode. As a result, dead members may not be immediately detected, which makes option D correct.

Option B is incorrect because there is no fixed 3-minute timer defined in FortiOS 7.6 that forces a return from active probing back to passive monitoring.

Option C is incorrect because passive SLA monitoring is based on TCP traffic , not ICMP traffic. ICMP is used for active probing , not passive monitoring.

Option E is incorrect because traffic subject to passive SLA monitoring cannot be offloaded to hardware . Passive SLA measurement requires software inspection of packets, which prevents NPU offloading.

Therefore, the two correct observable impacts of configuring the probe mode as Prefer Passive are A and D .

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 .

In Fortinet SD-WAN architecture, underlay and overlay have distinct meanings:

Underlay links are the physical or logical transport networks that provide basic IP connectivity (for example, broadband, MPLS, LTE/5G).

Overlay links are virtual tunnels (such as IPsec VPNs) built on top of the underlay , providing abstraction, routing control, and segmentation.

Option B is correct.

Overlay links (for example, IPsec tunnels used in SD-WAN and ADVPN) decouple routing from the physical transport. This allows dynamic path selection, segmentation, and flexible routing policies independent of the underlay. Providing routing flexibility is a core purpose of overlays in SD-WAN.

Option D is correct.

Wireless connections such as LTE or 5G can be used as underlay transports, and overlay tunnels can be built over them . Fortinet SD-WAN fully supports building IPsec overlays on wireless underlays, making wireless links valid for overlay construction.

Why the other options are incorrect:

Option A is incorrect because a VLAN is a Layer 2 segmentation mechanism, not an SD-WAN overlay link.

Option C is incorrect because FortiLink is used for internal management and switch/AP connectivity, not as a WAN underlay for SD-WAN.

Option E is incorrect because underlay links can be wired or wireless ; they are not limited to wired connections.

Therefore, the two correct statements are B and D .

From the SD-WAN monitor in FortiManager:

" The SD-WAN monitor provides a summary view of the branch devices and their members. In the scenario shown, it is clear that branch2_fgt is missing SLA configuration for one member, as evidenced by the lack of performance metrics. The monitor also shows only two branches in the current topology, allowing quick assessment of branch health and configuration completeness. "

This kind of visibility is vital for proactive monitoring and rapid troubleshooting in SD-WAN environments.

From the SD-WAN rule configuration (service edit 1, “Critical-DIA”), the rule uses mode sla and specifies:

set priority-members 1 2

This means, for traffic matching SD-WAN rule ID 1, FortiGate prefers member 1 first , then member 2 , but only if the selected member meets the SLA requirements.

From the SD-WAN event log , the message explicitly states:

Member status changed. Member out-of-sla.

The log includes Member: 1

This indicates SD-WAN member 1 is now out of SLA immediately after the log is generated.

From the SD-WAN member status output:

Member(1) corresponds to interface port1

Member(2) corresponds to interface port2

Because member 1 (port1) is out of SLA, FortiGate cannot use it for an SLA-based rule at that moment. With the rule configured for priority-members 1 2 , FortiGate will immediately steer matching traffic using the next eligible priority member that still meets the SLA, which is member 2 (port2) .

Therefore, immediately after the log messages are displayed, FortiGate steers the traffic for SD-WAN rule ID 1 using port2 , which corresponds to Option B .

You are right , and thank you for calling this out with the official Fortinet documentation reference.

Let’s correct QUESTION NO: 81 strictly according to Fortinet SD-WAN Architecture guidance and the FCSS SD-WAN 7.6 design principles .

Below is the corrected and verified answer , rewritten exactly in your required format .