Pass the Fortinet Certified Solution Specialist FCSS_NST_SE-7.6 Questions and answers with Dumpstech

To determine the type of policy route, we must interpret the specific flags and fields visible in the diagnose firewall proute list (or similar kernel table) output provided in the exhibit

Identify Key Indicators:

The most critical field in the output is vwl_service=1(test123).

It also lists vwl_mbr_seq=1 5.

Decode the Terminology:

vwl: This stands for Virtual WAN Link. In FortiOS, "Virtual WAN Link" is the legacy internal name for the SD-WAN feature. Even in newer firmware versions (7.x), the kernel and CLI debugs often still refer to SD-WAN objects as vwl.

vwl_service: This specifically refers to an SD-WAN Rule (also known as an SD-WAN Service). The name (test123) is the name given to that specific SD-WAN rule by the administrator.

Evaluate the Options:

A & D (Regular Policy Route): Standard policy routes (configured under config router policy) do not carry the vwl_service tag. They are typically identified by simple gateway or interface instructions without the SD-WAN service abstraction.

B (ISDB Route): While SD-WAN rules can use the Internet Service Database (ISDB) as a destination, the structure of the route entry shown here—specifically defined by a vwl_service ID—classifies it fundamentally as an SD-WAN rule, regardless of the destination object.

C (An SD-WAN rule): The presence of vwl_service and vwl_mbr_seq (SD-WAN member sequence) definitively identifies this entry as a rule generated by the SD-WAN subsystem.

Conclusion: The output shows a route controlled by the SD-WAN engine (vwl), confirming it is an SD-WAN rule.

When the "auxiliary session" setting is enabled (typically via config system npu or implicitly for ECMP on NP6/NP7 processors), the FortiGate alters how it manages sessions to support hardware offloading for traffic that might switch interfaces (like ECMP or SD-WAN).

B. FortiGate accelerates all ECMP traffic to the NP6 processor:

The primary purpose of enabling auxiliary sessions is to ensure that ECMP traffic can be fully offloaded (accelerated) by the NPU. Without auxiliary sessions, if the kernel or routing engine switches a flow to a different outgoing interface (due to load balancing), the NPU might not recognize the flow for that new interface and would send the packet back to the CPU (slow path). Auxiliary sessions prevent this by pre-populating the NPU with the necessary information for all valid paths.

D. FortiGate creates two sessions in case of a routing change:

Technically, the FortiGate creates the primary session (for the currently selected path) and an auxiliary session (for the alternative path). In a standard two-path ECMP scenario, this results in "two sessions" existing in the session table for the same flow. This ensures that if a routing change occurs (e.g., the flow shifts to the second path), the traffic continues to be processed by the NPU without interruption or re-evaluation by the CPU.

Comprehensive and Detailed 150 to 200 words of Explanation From Exact Extract of Network Security 7.6 documents:

The output on FGT-01 confirms that the device is actively encapsulating traffic and sending it as ESP packets (Protocol 50) out of port1 towards the IP address 97.86.16.52. The logs show outgoing packets, which confirms FGT-01 is attempting to initiate or maintain the tunnel and that NAT-Traversal is not being used (as it uses raw ESP).

The output on FGT-02, however, displays (no packets captured). This is significant because the sniffer command diagnose sniffer packet any 'esp' captures traffic at the network interface level (ingress), regardless of whether a matching VPN configuration exists on the receiving unit. The absence of packets proves that the ESP traffic generated by FGT-01 is physically not arriving at FGT-02's interface.

This behavior is explained by two primary factors:

Option A (Blocking): An intermediate device, such as an ISP router or firewall, is dropping Protocol 50 traffic. Unlike UDP 500/4500, raw ESP is often blocked by default on many networks or legacy devices.

Option C (Routing/Misconfiguration): If the administrator configured the wrong remote peer IP on FGT-01, the packets are being routed to a different destination entirely. Consequently, they never arrive at FGT-02 to be captured.

Option B is incorrect because even without a configured VPN tunnel, the sniffer would still display the incoming ESP packets if they were reaching the interface. Option D is incorrect because FGT-01 is sending ESP, making 'esp' the correct filter.

To understand why Type 5 LSAs (AS External LSAs) are missing from the Link-State Database (LSDB), we must look at how OSPF generates and propagates them:

A. There is no autonomous system border router (ASBR) in the network:

Reason: Type 5 LSAs are exclusively generated by an ASBR to advertise routes redistributed from other protocols (like Static, BGP, or RIP) into the OSPF domain. If no router is configured to redistribute external routes (acting as an ASBR), no Type 5 LSAs are created in the first place.

C. The local router is located in a stub area:

Reason: By definition, a Stub Area (and a Totally Stubby Area) prevents Type 5 LSAs from entering. The Area Border Router (ABR) connecting the stub area to the backbone filters out all Type 5 LSAs to reduce the size of the LSDB and routing table for routers inside that area. Instead, a default route is usually injected.

Why other options are incorrect:

B: While database filtering exists, standard prefix-list filtering typically affects the routing table (RIB) generation, not the underlying LSDB propagation of Type 5 LSAs, or it is less common than the architectural reasons (Stub/No ASBR).

D: IP Protocol 89 is the transport for OSPF itself. If this were blocked, the OSPF adjacency would not form at all, meaning the router would receive no LSAs (Type 1, 2, etc.), not specifically just Type 5.

To solve this high CPU usage scenario involving the ipsengine, we must understand the specific functions of the diagnose test application ipsmonitor commands shown in the troubleshooting steps.

Analyze the Situation:

Exhibit: The diagnose sys top output shows the ipsengine process is in a run state (R) consuming 99% CPU.

Previous Action: The administrator already ran diagnose test application ipsmonitor 5.

Result: The CPU usage did not drop.

Understand the Commands:

diagnose test application ipsmonitor 5: This command toggles IPS Bypass Mode. When enabled, the IPS engine lets traffic pass through without inspection.

Implication: If the CPU was high due to traffic volume, enabling bypass would drop the CPU load immediately.

Failure: Since the CPU remained at 99% after bypass, the ipsengine process is likely frozen, stuck, or in an internal infinite loop unrelated to the current traffic flow. The process itself is the problem, not the traffic volume.

Evaluate the Solution (Option B):

diagnose test application ipsmonitor 2: This command toggles the IPS engine's Enable/Disable status.

Because the engine is stuck (bypass failed to relieve pressure), the "Immediate action" required is to stop or restart the process entirely.

Running option 2 effectively disables/kills the stuck IPS engine instance, which will immediately drop the CPU usage to near zero. (It can then be toggled again to restart it).

Why other options are incorrect:

A (Reduce signatures): This is a tuning measure for normal operation, not an immediate fix for a stuck process at 99% CPU.

C (Disable IPS on policies): This is a configuration change that takes time and requires a commit; it is not the most immediate diagnostic tool available.

D (Bypass all IPS engines): This describes the action of command 5 (Bypass), which the prompt explicitly states was already performed and failed.