FCSS_NST_SE-7.6 Fortinet NSE 6 - Network Security 7.6 Support Engineer Free Practice Exam Questions (2026 Updated)

https://community.fortinet.com/t5/FortiGate/Technical-Tip-FortiGate-Static-URL-filter-actions-explained/ta-p/206632

The study guide states:

“The kernel memory slabs are collections of objects with a common purpose. The kernel uses them to store information in memory.”

It also gives the exact calculation rule:

“Total slab size = available objects x object size”

From the exhibit:

tcp_session 3 5 1500 ...

So:

available objects = 5

object size = 1500

Therefore:

Total slab size = 5 × 1500 = 7500 kB

That makes D correct, and it is associated with the kernel , not user space.

Why the other options are wrong:

A is wrong because sctp_session 0 0 1600 ... gives 0 × 1600 = 0 , but slabs are associated with the kernel , not user space.

B is wrong because ip_session 1 3 1200 ... gives 3 × 1200 = 3600 , but again slabs are kernel memory, not user space.

C is wrong because ip6_session 0 0 1300 ... gives 0 × 1300 = 0 , not 1300.

Parallel Path Processing (PPP) in FortiOS refers to the system’s ability to evaluate and select among multiple processing paths—often involving dedicated network processors, content processors, or CPU-based workflows—to optimally process packets. The official documentation highlights that the PPP engine dynamically selects which hardware or software path to use for each session based on session characteristics, policy configuration, and traffic type. This dynamic selection results in optimal throughput and resource utilization.

The document specifies that PPP assesses several processing paths in parallel, using decision logic to determine whether a session should be offloaded to specialist hardware (like NP6, CP9, etc.) or stay in the CPU path, ensuring that each packet is handled by the most efficient available method under current load and policy. Hardware and software configurations both influence this outcome, but it is the PPP engine ' s decision-making that defines the optimal path per session.

The BGP debug output shows session information for peers, including state details. According to official Fortinet BGP documentation, if the session state with a peer does not show " Idle, " " Active, " or " Connect, " but instead shows " Established, " " Up, " or related counters (e.g., messages sent/received or uptime), it indicates the session is operational. In this scenario, the peer 10.127.0.75 is the only one showing a positive indication of a live, established session. Other options like neighbor-range configuration, AS mismatch, or route-maps blocking prefixes are not supported by evidence provided in a simple BGP session state debug, nor does the output show errors relating to local or remote AS issues.

The correct interpretation comes from Fortinet ' s BGP troubleshooting guide, which outlines how to read session status and neighbor states in debug and summary outputs.

To capture encrypted IPsec phase 2 (ESP) traffic between two FortiGate devices, the correct protocol filter to use is ip proto 50. According to the Fortinet official sniffing and debugging documentation, ESP (Encapsulating Security Payload) is used for encrypted phase 2 payload transfer and always uses IP protocol number 50. Running the command diagnose sniffer packet any ' ip proto 50 '  captures only ESP packets, which represent the encrypted traffic—whether originating or transiting the device.

If there is no NAT device between FortiGates, ESP is not encapsulated in UDP (thus not on UDP port 4500; if NAT-T were required, packets would be UDP-encapsulated, but the scenario explicitly says NAT is not in use). UDP port 500 is for IKE control (negotiation) traffic, and AH (Authentication Header, ip proto 51) is not used for encryption in standard IPsec phase 2 with ESP.

This matches the official CLI reference from Fortinet for VPN and traffic analysis.

**

The key point is that the two VPNs are dynamic dialup IPsec tunnels on the same interface and both are using IKEv1 main mode . In this design, FortiGate cannot reliably distinguish which dialup phase1 to match before phase 1 completes.

The uploaded Network Security Support Engineer 7.6 Study Guide shows that XAuth happens only after phase 1 is already established:

“The IKE real-time debug shows, after phase 1, the exchange of extended authentication (XAuth) packets… You can also see the CFG_REPLY, showing the XAuth user and group name.”

That means the user group is learned too late to be used for selecting the correct phase1 definition. So the fix must be applied to the phase1 matching method itself , not to XAuth.

The FortiOS administration guide gives the exact rule for this scenario:

“When the remote VPN peer has a dynamic IP address and is authenticated by a pre-shared key you must select Aggressive mode if there is more than one dialup phase 1 configuration for the interface IP address.”

The correct answer is A .

The study guide explains the IKEv2 exchange order very clearly:

“The initial exchanges are: IKE_SA_INIT and IKE_AUTH.”

“Create_Child_SA exchange: Creates a new child SA or rekeys an existing child SA.”

It also states:

“After successful IKE_SA_INIT and IKE_AUTH exchanges, the CHILD_SA exchange takes place. In this exchange, the peers negotiate the CHILD_SA and the traffic selectors — traffic selector responder (TSr) and traffic selector initiator (TSi).”

That is why A is correct: if the tunnel was initially brought up successfully , then the initial exchanges already succeeded. A later problem during CREATE_CHILD_SA , especially with traffic selectors/phase 2 selectors , can cause the tunnel to fail during rekey or child-SA renegotiation.

Why the other options are wrong:

B is wrong because proposal mismatch for the IKE SA is handled during IKE_SA_INIT , not after the tunnel is already up. The study guide says IKE_SA_INIT negotiates the security settings to protect the IKE traffic

C is wrong because a pre-shared key mismatch is part of authentication and would prevent successful initial establishment during IKE_AUTH . The study guide shows that after IKE_AUTH, “authentication succeeded” and “established IKE SA” when it works

D is wrong because a Diffie-Hellman mismatch belongs to IKE_SA_INIT , which happens before the tunnel comes up. The study guide also states: “By IKEv2 design, no Diffie-Hellman public key is exchanged during an IKE_AUTH exchange.”

So the verified answer is: A .

The exhibit shows a FortiGate configuration under config system fortiguard related to web filtering and FortiGuard options. There is a line:

set webfilter-force-off enable

According to official Fortinet documentation, the " webfilter-force-off " option, when enabled, causes the FortiGate to bypass web filtering for all traffic—even if a web filter profile is applied to a policy. This override is typically used for troubleshooting or performance reasons and is documented as an explicit bypass feature.

If an administrator wants to enforce web filtering inspection, this setting must be disabled. The correct way to restore web filtering functionality is to run:

set webfilter-force-off disable

Once done, traffic passing through policies with web filter profiles will be inspected and filtered as per configuration. Other settings such as timeout or cache TTL do not bypass web filtering; they only affect operational nuances.

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.

Analyze the " Send to Application Layer " Message:

The most critical line in the debug output is: id=65308 ... func=av_receive ... msg= " send to application layer "

Meaning: This message indicates that the FortiGate kernel is handing the packet over to a user-space daemon (specifically the WAD/Proxy process, indicated by av_receive handlers) for deep inspection.

Implication: This behavior is the hallmark of Proxy-based inspection. In Flow-based inspection, the traffic is handled by the IPS engine (often within the kernel or via specific IPS handlers like ips_measure), and you would not typically see a " send to application layer " message for standard web filtering.

Evaluate Option B (Firewall Policy Mode):

Since the traffic is being sent to the application layer proxy, the Firewall Policy controlling this traffic (Policy ID 1, as seen in Allowed by Policy-1) must be configured with Inspection Mode = Proxy. If it were Flow-based, the traffic would stay in the flow path. Thus, Option B is correct.

Evaluate Option C (Web Filter Profile Mode):

In FortiOS, when a firewall policy is set to Proxy-based inspection, the security profiles (like Web Filter) applied to that policy also operate in Proxy-based inspection mode. The presence of the av_receive function confirms that the content inspection (Web Filter/AV) is being performed by the proxy engine. Thus, Option C is correct.

Why Option A is Incorrect (NPU Offload):

The output shows npu_state=0x100. In the context of a flow trace where traffic is being " sent to application layer, " this confirms the session is not fully offloaded to the NPU (Network Processor). Offloaded traffic (Fast Path) is handled by the hardware and would not generate these specific CPU-level debug logs for the payload inspection phase. The proxying process requires CPU intervention.

Why Option D is Incorrect (Port Mapping):

While valid protocol mapping is necessary for inspection, the specific debug output shown is a direct result of the Inspection Mode (Proxy vs. Flow). The observation of the traffic moving to the application layer is primarily caused by the policy and profile mode settings, making B and C the direct " observations " derived from the log data.

The issue is caused by the strict matching logic of the configured Prefix List.

Current State: The rule is edit 1 with set prefix 172.16.0.0 255.255.0.0 and both ge (greater than or equal) and le (less than or equal) are unset.

Behavior: When ge and le are unset, FortiOS requires an exact match of the subnet mask. The current rule only matches the exact network 172.16.0.0/16. It denies 172.16.52.0/24 because the mask (/24) does not match the rule ' s mask (/16).

To fix this and inject 172.16.52.0/24, you must modify the list to match the /24 mask:

A. Add another entry to the prefix list to specifically allow the 172.16.52.0/24 network:

Creating a new rule (e.g., edit 2) with set prefix 172.16.52.0 255.255.255.0 will provide an exact match for the incoming route, allowing it to pass the distribute-list.

B. Change the ge value to 17:

By configuring set ge 17 on the existing rule (conceptually 172.16.0.0/16 ge 17), you change the logic from " exact match " to " range match " .

This configuration tells the router to match any prefix starting with 172.16.x.x that has a subnet mask length of 17 or greater.

Since the incoming route is a /24, and 24 is greater than 17, the route will match the prefix list and be accepted.

Why other options are incorrect:

C: The option text appears to read " Change the ... value to 16 " . If this refers to le 16, it would enforce the mask to be exactly /16 or less, which still excludes /24.

D: Changing the default behavior to implicit allow defeats the purpose of a filter (security control) and is not a standard configuration step for fixing a single missing route.

When FortiGate performs SSL certificate inspection with default settings, it checks if the Server Name Indication (SNI) matches either the Common Name (CN) or any Subject Alternative Name (SAN) in the server certificate. If there is no match, FortiGate does not block the connection; instead, it uses the CN value from the certificate ' s subject field to continue web filtering and categorization.

This behavior is described in the official Fortinet 7.6.4 Administration Guide:

“Check the SNI in the hello message with the CN or SAN field in the returned server certificate: Enable: If it is mismatched, use the CN in the server certificate.” This is the default (Enable) mode, which differs from the Strict mode that would block the mismatched connection.

By default, this policy ensures service continuity and prevents disruptions due to certificate mismatches, allowing FortiGate to log and inspect based on the CN even when the requested SNI does not match. It provides a balance between connection reliability and the accuracy of filtering by certificate identity, allowing security policies to remain functional without unnecessary blocks. This approach is recommended by Fortinet to maintain usability for end-users while still supporting granular inspection.

The correct answer is A .

The debug output is for an HTTPS request and shows a hostname value. The study guide explains that with SSL certificate inspection, FortiGate extracts the FQDN from either:

“TLS extension server name indication (SNI)”

“SSL certificate common name (CN)”

So the hostname shown in the real-time web-filter debug can be derived from the SNI in the client request or, if needed, from the CN in the server certificate. That makes A correct.

Why the other options are wrong:

B is wrong because the study-guide example for web-filter real-time debug explicitly says: “This slide shows an example of real-time debug output when the URL to categorize isn ' t in the FortiGuard cache.” In these debugs, cat=255 appears before the final lookup result, so this does not indicate a local-cache hit.

C is wrong because ftgd-allow is the action , not the profile name. The debug line shows the action as action=9 (ftgd-allow) while the profile shown is profile= ' default ' . FortiOS web-filter logs also use the profile field separately from the action field

D is wrong because the final category shown is url_cat=52 , not 255. The study guide’s example shows the same pattern: an initial cat=255 in the request line, followed by the resolved result cat=52 url_cat=52

So the verified answer is: A .

The correct answer is B .

The study guide explicitly states: “IKE version 2 does not interoperate with IKE version 1, but they share enough of the header format that both versions can unambiguously operate over the same UDP port.”

That directly proves B .

Why the other options are wrong:

A is wrong because the study guide shows authentication methods as Asymmetric for IKEv2 and Symmetric for IKEv1

C is wrong because the study guide does not say they use the same TCP port; instead, it specifically says they can operate over the same UDP port

D is wrong because the study guide states: “IKEv2 does not use the concept of phase 1 or phase 2” , even though FortiOS CLI/GUI still uses those terms for configuration purposes

To determine the cause of the failure, we must analyze the IKEv2 debug output provided in the exhibit (image_ad3dc6.jpg):

Identify the Negotiation Phase:

The debug log shows: responder received CREATE_CHILD exchange.

In IKEv2, the CREATE_CHILD_SA exchange is used to create new Child SAs (Phase 2) or to rekey existing ones.

The fact that the tunnel was previously " brought up successfully " implies the initial IKE SA (Phase 1) is stable, and this error is occurring specifically during a rekey event, which often involves Perfect Forward Secrecy (PFS).

Analyze the Proposals (The Mismatch):

Incoming Proposal (Remote Peer):

The remote peer sends a proposal containing two Diffie-Hellman groups: type=DH_GROUP, val=MODP2048 (Group 14) and type=DH_GROUP, val=MODP1536 (Group 5).

My Proposal (Local FortiGate):

The local FortiGate configuration expects: type=DH_GROUP, val=MODP3072 (Group 15).

Result of the Negotiation:

The debug output concludes with: no proposal chosen and Negotiate SA Error.

This error occurs because the local FortiGate cannot find a common Diffie-Hellman group between what it requires (Group 15) and what the peer is offering (Groups 14 or 5).

While this is technically a mismatch occurring during the Phase 2 (Child SA) creation, " A Diffie-Hellman mismatch " (Option A) is the precise root cause identified in the logs.

Why other options are incorrect:

B: The log shows received create-child request, confirming that UDP traffic is reaching the device and is not blocked.

C: The failure is in the CREATE_CHILD exchange (Phase 2/Rekey), not the IKE_SA_INIT or IKE_AUTH (Phase 1) exchanges.

D: While the mismatch is occurring within the Phase 2 definitions, Option A is the specific technical reason for the no proposal chosen error shown in the DH_GROUP lines.

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.