NSE4_FGT_AD-7.6 Fortinet NSE 4 - FortiOS 7.6 Administrator Question and Answers

“In this use case, FortiSASE acts as an SWG and distributes a proxy auto-configuration (PAC) file to end users, enabling the FortiSASE SWG service as an explicit web proxy. SWG deployment secures only web traffic protocols, such as HTTP and HTTPS.”

“All other nonweb traffic bypasses FortiSASE and is forwarded directly to the internet.”

Technical Deep Dive:

The correct answer is A .

In agentless SWG-based SIA , FortiSASE is operating as an explicit web proxy using a PAC file . That model captures only web protocols , specifically HTTP and HTTPS . It does not create a full tunnel for the endpoint like agent-based FortiClient deployment does.

So the design implication is simple: nonweb traffic does not traverse FortiSASE in this onboarding model. It goes directly to the internet from the endpoint.

Why the other options are wrong:

B is wrong because this is not split-tunnel VPN behavior.

C is wrong because FWaaS does not automatically capture nonweb traffic in the agentless SWG model.

D is wrong because SWG does not redirect nonweb traffic to FortiExtender.

This is an important deployment distinction:

Agent-based SIA can steer broader endpoint traffic through FortiSASE.

Agentless SWG SIA secures only browser-based web traffic.

“By default, you can select only a single interface as the incoming interface and a single interface as the outgoing interface. This is because the option to select multiple interfaces, or any interface in a firewall policy, is disabled on the GUI. However, you can enable the Multiple Interface Policies option on the Feature Visibility page to disable the single interface restriction.”

“You can also specify multiple interfaces, or use the any option, if you configure a firewall policy on the CLI, regardless of the default GUI setting.”

Technical Deep Dive:

The correct answer is D .

The policies are identical except for the incoming interface : one is for Sales and one is for Engineering . FortiGate GUI policy creation normally restricts you to one incoming interface per policy. To consolidate both into a single GUI policy, the administrator must enable Multiple Interface Policies so both port1 and port2 can be selected in the same rule.

Why the others are wrong:

A is not enough, because policy matching also includes the incoming interface , not just the source subnets.

B changes the network design and is unnecessary.

C would work too broadly by matching traffic from any interface, which is not the intended controlled consolidation.

A matching CLI-style concept would be:

config firewall policy

edit < id >

set srcintf " port1 " " port2 "

set dstintf " < server-interface > "

set srcaddr " Sales_Subnet " " Engineering_Subnet "

set dstaddr " < web-server > "

set service " HTTP " " HTTPS "

set action accept

next

end

That preserves a single policy while still being specific about which interfaces are allowed.

“ Rate-based IPS signatures also allows you to detect anomalies, which are unusual behaviors in the network...”

“There are two ways to add predefined signatures to an IPS sensor. One way is to select the signatures individually... The second way to add a signature to a sensor is using filters.”

“ You can also add rate-based signatures to block specific traffic when the threshold is exceeded. On the CLI, If you set the command rate-mode to periodical, FortiGate triggers the action when the threshold is reached during the configured Duration time period. ”

Technical Deep Dive:

The correct answer is C. Use IPS signatures, rate-mode periodical option.

The guide is explicit that this behavior belongs to rate-based IPS signatures . The question asks for blocking traffic when a signature is triggered a certain number of times within a defined interval. That is exactly what rate-mode periodical does: it evaluates the trigger count over the configured duration window and then applies the configured IPS action when the threshold is met.

Why the other options are wrong:

A is wrong because rate-mode 60 is not the documented syntax or method.

B is wrong because packet logging records packets; it does not implement threshold-based blocking logic.

D is wrong because the guide ties rate-mode periodical to rate-based signatures , not to IPS filters as the mechanism for this threshold behavior.

Operationally, this is used for anomaly-style detection, similar in concept to lightweight rate-based protection. A typical CLI pattern is along these lines:

config ips sensor

edit " custom-ips "

config entries

edit 1

set rule < signature_id >

set rate-mode periodical

set rate-count < threshold >

set rate-duration < seconds >

set action block

next

end

next

end

This works best when applied only to relevant protocols and signatures, because broad use of rate-based signatures can consume more resources and increase false-positive risk.

With full SSL inspection, FortiGate performs a man-in-the-middle process: it decrypts the HTTPS session, inspects it, then re-encrypts it. To do this, FortiGate presents a substitute certificate to the client, signed by the CA certificate configured in the SSL/SSH inspection profile (for example, Fortinet_CA_SSL or a custom enterprise CA).

Browsers will show certificate warning errors when the issuing CA is not trusted by the client device/browser trust store. This only happens for HTTPS because certificates are used in TLS; HTTP has no certificate exchange, so no warning appears.

Why the other options are incorrect:

A: Allowing invalid server certificates affects whether FortiGate blocks/permits connections to sites with bad certs; it does not fix the client warning about FortiGate’s substituted cert.

B: Proxy vs flow inspection mode does not inherently cause certificate warnings; the warning is about trust of the signing CA.

D: Missing extensions is not the typical reason across “any HTTPS website”; the standard reason is the client does not trust the FortiGate inspection CA

In the FortiGate Cloud-Native Firewall (CNF) for AWS architecture, traffic from workloads (such as an EC2 instance) in the customer VPC is redirected to the security service (FortiGate CNF) using AWS Gateway Load Balancer (GWLB) technology.

The key AWS component that must exist inside the customer VPC to steer workload traffic to the GWLB is the:

Gateway Load Balancer Endpoint (GWLBe)

This endpoint is what the customer VPC routes point to (for example, default route or subnet route entries), enabling transparent insertion of the FortiGate CNF inspection path for EC2 traffic.

Why the other options are not correct:

A: CNF does not “create the customer VPC” (that is customer-owned), and “GWLBe” is the only relevant created item here, not the whole VPC.

C: Customer VPC is not created by CNF, and GWLB is typically part of the CNF service side; the question specifically asks what must be created to handle traffic from the EC2 instance (that requires GWLBe in the customer VPC).

D: CNF does not create the Internet Gateway (IGW) in the customer VPC, and IGW is not the required CNF-created component for steering traffic to FortiGate CNF.

“This slide shows the SD-WAN rule lookup process. SD-WAN rules are essentially policy routes.”

“FortiGate performs a forwarding information base (FIB) lookup for the packet destination IP (dstip). If the resolved interface for the fib-best-match isn’t an SD-WAN member, then FortiGate moves on to the next rule. This behavior follows the key routing principle: SD-WAN rules are skipped if the best route to the destination isn’t an SD-WAN member .”

“If the resolved interface is an SD-WAN member, then FortiGate looks for one or more acceptable members in the oif list... An acceptable member is an alive member that has a route to the destination. This behavior follows the key routing principle: SD-WAN rules are skipped if none of the configured members in the rule have a valid route to the destination .”

“Because regular policy routes have precedence over any other routes...”

“Also note that policy routes have precedence over SD-WAN rules, and over any routes in the FIB.”

Technical Deep Dive:

The correct answers are A, C, and E .

A is correct because an SD-WAN rule is not enough by itself. A selected member must also be alive and have a valid route to the destination. If none of the members referenced by the rule can actually reach the destination, the rule is skipped.

C is correct because a regular policy route is evaluated before SD-WAN rules. This is a classic exam trap. FortiGate treats SD-WAN steering like policy-route logic, but standard policy routes still win if they match and are valid.

E is correct because FortiGate first checks the FIB best match . If that best route resolves to an interface that is not an SD-WAN member, FortiGate skips the SD-WAN rule and continues.

Why the others are wrong:

B is false because SD-WAN rules do not have precedence over everything; regular policy routes do.

D is false because the number of available routes is not the deciding rule. Even with only one route, SD-WAN can still steer traffic if the routing and member conditions are met.

Operationally, think of SD-WAN routing in this order: policy route check → SD-WAN rule lookup → standard FIB fallback . On FortiGate, the practical validation commands are:

get router info routing-table all

diagnose sys sdwan service

diagnose firewall proute list

That combination lets you confirm whether a packet is being captured by a policy route, whether an SD-WAN rule has acceptable members, and what the FIB currently resolves for the destination.

“When using FortiGuard servers for DNS, FortiOS uses DNS over TLS (DoT) by default to secure the DNS traffic. New FortiGuard DNS servers have been added as primary and secondary servers.”

Technical Deep Dive:

The correct answer is C. It uses DNS over TLS .

This is a direct default-behavior question. If you configure FortiGuard servers as DNS servers and do not change anything else, FortiGate uses DoT rather than plain DNS. That means the DNS session is encrypted, which protects DNS queries from simple interception or tampering on the path.

Why the other options are wrong:

A is standard clear-text DNS behavior, not the FortiGuard DNS default stated in the guide.

B is incorrect because the guide specifically says DNS over TLS , not DNS over HTTPS.

D is incorrect; the guide does not describe UDP 8888 as the default transport for this DNS use case.

Operationally, this matters because FortiGate relies on DNS not only for client-facing services, but also for resolving objects and securely reaching cloud-based services. Using DoT improves confidentiality for those DNS lookups.

“FortiSASE provides secure access to remote users for the following use cases:

• SIA enables secure web browsing for remote users to protect from known and unknown threats

• SPA enables explicit application access under a zero-trust access or with SD-WAN integration to ensure secure application access

• SSA addresses shadow IT visibility challenges and safeguards data loss prevention ”

“FortiCASB provides cloud-based and API-based features to enable deep inspection of SaaS applications to enable detailed monitoring, analysis, and reporting features... Data loss prevention (DLP) helps to identify, monitor, and protect organizational data at rest and in motion. ”

Technical Deep Dive:

The correct answer is C. Secure SaaS access (SSA) .

The question gives two very specific requirements:

Shadow IT visibility

Prevent sensitive files from leaving the organization without approval

The study guide maps both directly to SSA . In FortiSASE, SSA aligns with SaaS governance and CASB-style controls. That is the right architecture when you need visibility into sanctioned and unsanctioned SaaS usage, plus DLP controls for uploads, sharing, and file movement.

Why the other options are wrong:

SIA focuses on securing internet browsing and remote web traffic.

SPA is for explicit zero-trust access to private applications.

SSD-WAN is not the FortiSASE method for SaaS visibility/DLP control.

In practice, SSA is the choice because it combines SaaS visibility, activity monitoring, and DLP-style enforcement . That lets an administrator detect shadow SaaS usage and apply controls such as blocking uploads, monitoring sharing events, or restricting file transfers based on policy. This is a CASB-oriented use case, not just generic web security.

Exact Extract:

“In IKEv1, there are two possible modes in which the IKE SA negotiation can take place: main, and aggressive mode. Settings on both ends must agree; otherwise, phase 1 negotiation fails and both IPsec peers are not able to establish a secure channel.”

“When both peers know each other ' s IP address or FQDN, you may want to use main mode to take advantage of its more secure negotiation. In this case, FortiGate can identify the remote peer by its IP address and, as a result, associate it with the correct IPsec tunnel.”

“FortiGate supports three DPD modes... The default DPD mode is On Demand .”

“ Diffie-Hellman (DH) ... is used during IKE SA negotiation. The use of DH in phase 1 is mandatory and can’t be disabled . You must select at least one DH group.”

Technical Deep Dive:

The correct answers are B and C .

B is correct because phase 1 fails when IKE mode settings do not match between peers. The study guide explicitly says phase 1 settings on both ends must agree. Since this is a static site-to-site tunnel and both peers know each other’s IP addresses, Main (ID protection) is the appropriate mode.

C is correct based on the exhibit: BR1-FGT appears bound to the wrong physical interface. The screenshot shows Interface = port1 , while the diagram/answer choice indicates the tunnel should be using port2 . If the phase 1 is bound to the wrong WAN interface, FortiGate sends IKE packets out the wrong path and phase 1 will not come up.

Why the others are not the fix:

A is not correct because DH is mandatory in phase 1. The issue is not “disable DH group 2” by itself; the real requirement is that the peers negotiate a compatible proposal. The option as written is not the proper corrective action from the guide.

D is not correct because DPD does not determine whether phase 1 can initially establish. It is a tunnel health/failure-detection feature after negotiation behavior, and On Demand is already the default mode.

According to the FortiOS 7.6 Administration Guide and Security Fabric documentation, automation stitches are designed to automate responses to security and system events across the network. A core characteristic of these stitches is their flexibility in action execution; specifically, multiple actions can run in parallel (Statement C). While the system allows for sequential execution with configurable delays between actions, the default behavior or configuration option allows for simultaneous responses, such as sending an email notification while simultaneously triggering a webhook or quarantining a host.

Furthermore, triggers can involve external connectors (Statement D). While many triggers are local to the FortiGate (such as reboots or log events), the Security Fabric allows the FortiGate to monitor and react to events from external components like FortiAnalyzer , FortiSIEM , or FortiClient EMS . For example, a FortiAnalyzer event handler can act as the trigger for a stitch on the root FortiGate. Statement A is incorrect because actions can target external systems like AWS Lambda or Slack which are not internal Fabric devices. Statement B is incorrect because each automation stitch is typically defined by a single trigger , though that trigger itself can be broad (e.g., " Any Security Rating Notification " ).

According to FortiOS 7.6 High Availability documentation, the FortiGate Cluster Protocol (FGCP) provides robust mechanisms for both link monitoring and stateful data synchronization. Link failover is a primary trigger for cluster renegotiation; if a monitored interface goes down—including when an administrator manually sets the interface to administratively down —the primary unit ' s priority is effectively reduced, triggering a failover to a secondary unit to ensure path continuity. 5 This is a standard method for testing HA failover behavior.

Furthermore, to achieve a seamless stateful failover where active sessions are not dropped, the FortiGate performs incremental synchronization of critical runtime data. 6 This specifically includes Forwarding Information Base (FIB) entries, which represent the compiled routing table, and IPsec Security Associations (SAs) . 7 By synchronizing IPsec SAs, the secondary unit 8 can resume encrypted tunnels immediately after a failover without requiring a f 9 ull IKE re-negotiation. 10 Statement A is incorrect because in-band and out-of-band management can coexist using reserved management interfaces and management-ip settings. 11 Statement C is incorrect because while heartbeat interfaces use link-local IPs in the 169.254.0.x range, the specific IP .2 is not universally required for all heartbeats and depends on the number of cluster members and serial numbers.

“To reduce the number of log messages generated and improve performance, you can enable a session table entry of dropped traffic. This creates the denied session in the session table and, if the session is denied, all packets for that session are also denied. This ensures that FortiGate does not have to perform a policy lookup for each new packet matching the denied session, which reduces CPU usage and log generation.”

“The CLI command is ses-denied-traffic. You can also set the duration for block sessions. This determines how long a session will be kept in the session table by setting block-session-timer in the CLI. By default, it is set to 30 seconds.”

Technical Deep Dive:

The correct answers are A and B .

When set ses-denied-traffic enable is configured, FortiGate creates a session-table entry for denied traffic . That means once traffic is denied, subsequent packets that belong to the same denied flow do not need a full policy lookup again. FortiGate can drop them immediately based on the existing denied-session entry. That directly confirms B .

Because FortiGate no longer re-evaluates every repeated denied packet in the same way, the device generates fewer logs and uses less CPU for repeated denied traffic. That is exactly why A is also correct.

Why the other two are wrong:

C is incorrect because block-session-timer 30 means 30 seconds , not 30 minutes. The denied session entry is kept in the session table for that duration.

D is incorrect because these settings do not disable session helpers. They only control how denied traffic is tracked in the session table.

In operational terms, this feature is useful when a host repeatedly retries traffic that FortiGate is already denying. Instead of doing a fresh lookup for every retry, FortiGate caches the denied decision temporarily and drops the repeated packets faster.

Based on the exhibit and the FortiOS 7.6 SSL/SSH Inspection documentation, the correct answer is C.

Understanding the Exhibit Configuration

In the SSL/SSH Inspection Profile, the following settings are shown:

Inspection method: Full SSL Inspection

Server certificate SNI check: Strict

This setting directly controls how FortiGate validates the Server Name Indication (SNI) provided by the client during the TLS handshake.

FortiOS 7.6 Behavior of “Server certificate SNI check”

FortiOS supports three modes for Server certificate SNI check:

Disable

No validation between SNI and server certificate.

Enable

FortiGate checks SNI against the certificate.

If mismatch occurs, FortiGate may still allow the session with reduced validation.

Strict

FortiGate enforces a strict match.

The SNI must match either the CN (Common Name) or one of the SAN (Subject Alternative Name) entries in the server certificate.

If the SNI does not match either CN or SAN, the TLS session is immediately terminated.

The exhibit clearly shows Strict selected.

Why Option C is Correct

With Strict enabled, FortiGate rejects the TLS connection when:

The SNI does not match the CN, and

The SNI does not match any SAN entry

This results in the connection being closed, not allowed with warnings or fallback behavior.

Therefore:

C. FortiGate will close the connection if the SNI does not match the CN or SAN fields is exactly the documented behavior.

Why the Other Options Are Incorrect

A: FortiGate does not fall back to using the CN for URL filtering when Strict is enabled.

B: There is no “accept with warning” behavior in Strict mode.

D: Incorrect logical condition. FortiGate does not require mismatch with both CN and SAN simultaneously; a mismatch with either valid field set is sufficient to close the connection.

According to the FortiOS 7.6 Troubleshooting and Administration guides, the diagnose debug flow command provides a step-by-step trace of how the FortiGate unit processes a packet.

First, the line " find a route: flag=00000000 gw-0.0.0.0 via port2 " indicates that during the routing table lookup, the FortiGate matched the destination against its default route (represented by 0.0.0.0) and determined that the egress interface is port2 . This confirms that the default gateway for this traffic is reachable via port2 (Statement A).

Second, the debug trace concludes with the messages " policy-2 Is matched, act-drop " and " Denied by forward policy check (policy 2) " . This explicitly indicates that the packet successfully matched the criteria for firewall policy ID 2, and the action configured for that policy is set to Deny (Statement D).

Statement B is incorrect because a Reverse Path Forwarding (RPF) failure would be indicated by a specific " reverse path check fail, drop " message, which is absent here. Statement C is incorrect because the output shows " proto=1 " , which corresponds to ICMP (Ping) traffic. UDP traffic would be identified as protocol 17.

From the routing table in the exhibit, there is already a static route for 172.20.1.0/24 pointing out port3 with:

Distance = 9

Priority = 2

Type = Static

In FortiOS, route selection prefers (in order) the route with the lowest administrative distance to a destination. Therefore, to make traffic to 172.20.1.0/24 go through port2 only, the administrator must ensure the port2 static route is more preferred than the existing port3 route.

Why C is correct

C. The existing static route through port3 must have the distance set to 11.

If the existing port3 route distance is increased to 11, then a new port2 route with distance 9 will be preferred (9 < 11). This makes the port3 route a backup route instead of the active one.

Why D is correct

D. The new static route must have the distance set to 9

Setting the new port2 route distance to 9 (and increasing the port3 route to 11 as in option C) ensures FortiGate selects the port2 route as the best route for 172.20.1.0/24.

Why A and B are not correct

A (priority 3): By itself it does not guarantee selection over the existing route, and FortiOS route choice is driven primarily by distance.

B (metric 1): Metric is not the primary selector for static route preference compared to administrative distance in this scenario.

So the two criteria that achieve the objective are:

Make the existing port3 route less preferred by increasing its distance (C)

Ensure the new port2 route uses the preferred distance (D)

In FortiOS 7.6, web filter profiles are inspection-mode dependent. Certain advanced web filtering features—such as daily category usage quota—are only supported when the firewall policy is operating in proxy-based inspection mode.

Why the profile is not visible

The profile restrictmedia-profile includes a daily category usage quota.

Daily quotas are a proxy-based web filtering feature.

If the firewall policy is configured with:

Inspection mode: Flow-based

Then FortiGate will not display proxy-only web filter profiles in the Web Filter drop-down list.

FortiGate automatically filters the available profiles based on feature compatibility with the policy’s inspection mode.

This behavior is explicitly documented in the FortiOS 7.6 Web Filtering and Inspection Mode Compatibility sections.

Why the other options are incorrect

A. Already referenced in another firewall policyWeb filter profiles can be reused across multiple policies. This does not hide them.

B. Firewall policy is in no-inspection mode instead of deep-inspectionSSL inspection depth affects HTTPS visibility, not whether a web filter profile appears in the drop-down list.

C. Naming convention restrictionFortiOS does not restrict profile selection based on naming conventions.

“Three different configurable thresholds define when FortiGate enters and exits conserve mode. If memory usage goes above the percentage of total RAM defined as the red threshold , FortiGate enters conserve mode.”

“If memory usage keeps increasing, it might exceed the extreme threshold . While memory usage is above this highest threshold, all new sessions are dropped. ”

“What actions does FortiGate take to preserve memory while in conserve mode?

• FortiGate does not accept configuration changes , because they might increase memory usage.”

“However, if the memory usage exceeds the extreme threshold, new sessions are always dropped , regardless of the FortiGate configuration.”

Technical Deep Dive:

The system performance output shows Memory: 2042076k total, 1837868k used (90%) . The configured thresholds shown are:

green = 82

red = 88

extreme = 89

Because memory usage is 90% , it is:

Above the red threshold (88%) → so FortiGate has entered conserve mode

Above the extreme threshold (89%) → so all new sessions are dropped

That makes A and D correct.

Why the others are wrong:

B is not stated anywhere in the study guide as an automatic outcome of conserve mode.

C is the opposite of what the guide says. In conserve mode, FortiGate does not accept configuration changes .

A useful verification command is:

diagnose hardware sysinfo conserve

Operationally, once a FortiGate crosses the red threshold , it starts protecting itself by limiting behavior that could increase memory usage. Once it crosses the extreme threshold , it becomes more severe and drops new sessions to keep the system from becoming unstable.

From the exhibits:

The Web Filter profile is configured with Feature set = Flow-based.

The Firewall policy is configured with Inspection mode = Proxy-based and has Web Filter enabled.

In FortiOS 7.6, security profiles that have a feature set selection (Flow-based vs Proxy-based) must match the inspection mode used by the firewall policy. If the profile’s feature set does not match the policy’s inspection mode, the profile behavior will not align with what the administrator expects (and in many cases FortiOS will prevent correct use/selection, or the feature behavior will not apply as intended).

That mismatch explains why the configured URL filter entry for www.facebook.com (set to Monitor) is not producing the expected result, and instead the session is being evaluated by category rating and blocked (shown as Malicious Websites on the FortiGuard block page).

Why the other options are not the best fit:

A: A web rating override is not shown in the exhibits, and nothing indicates an override misconfiguration.

C: While the policy inspection mode could be changed, the root cause shown is the profile feature set mismatch (profile is Flow-based).

D: The URL filter action shown is Monitor, which would not produce a block page by itself.

According to the FortiOS 7.6 Study Guide and Parallel Path Processing documentation, flow-based antivirus inspection is designed to provide security with minimal impact on performance.

First, a defining characteristic of modern flow-based AV (specifically in its " hybrid " mode) is that FortiGate buffers the whole file but transmits to the client at the same time (Statement A). This behavior allows the client to start receiving data immediately to prevent session timeouts, while the FortiGate reassembles the file in memory to perform a signature check before the final packet is released.

Second, starting with recent FortiOS versions including 7.6, flow-based inspection uses a hybrid of the scanning modes (Statement B). Previously, flow mode offered " Quick " or " Full " scans; now, it combines these techniques to offer a balance between the speed of stream-based scanning and the thoroughness of archive inspection.

Third, the primary motivation for selecting this mode is that flow-based inspection optimizes performance compared to proxy-based inspection (Statement D). It processes traffic in a single pass using the IPS engine, avoiding the overhead associated with the WAD (proxy) process. Statement C is incorrect because if a virus is detected, the last packet is withheld and the connection is reset to prevent the file from being completed. Statement E is less accurate as the IPS engine loads the AV engine to perform the task rather than acting as a " standalone " entity in the context of file scanning.

From the exhibits:

System performance output

Memory used: 90%

Free memory: ~5%

Default memory thresholds (FortiOS 7.6)

memory-use-threshold-green 82%

memory-use-threshold-red 88%

memory-use-threshold-extreme 89%

Because memory usage (90%) exceeds the extreme threshold (89%), the FortiGate enters conserve mode.

Effects of conserve mode (FortiOS 7.6 – verified)

B. FortiGate has entered conserve mode.

Correct

When memory usage exceeds the red/extreme threshold, FortiGate automatically enters conserve mode.

This is exactly the condition shown in the system performance output.

D. Administrators can change the configuration.

Correct

Even in conserve mode:

Administrators can still log in (GUI, SSH, console)

Configuration changes are allowed

FortiGate does not lock configuration access during conserve mode.

This behavior is explicitly documented in the FortiOS 7.6 Conserve Mode section.

Why the other options are incorrect

A. Administrators can access FortiGate only through the console port.

Incorrect

Network access (GUI/SSH) is still available in conserve mode unless otherwise restricted.

Console-only access is not a conserve-mode requirement.

C. FortiGate drops new sessions.

Incorrect (as a general statement)

FortiGate may drop or bypass new inspection-required sessions depending on fail-open/fail-close settings.

It does not universally drop all new sessions, so this statement is not always true.

“The only security features you can apply using SSL certificate inspection mode are web filtering and application control... Note that while offering some level of security, certificate inspection does not allow FortiGate to inspect the flow of encrypted data.”

“To perform SSL inspection on traffic flowing through the FortiGate device, you must allow the traffic with a firewall policy and apply an SSL inspection profile to the policy... For antivirus or IPS control, you should use a deep-inspection profile.”

“When you use deep inspection, FortiGate impersonates the recipient of the originating SSL session, and then decrypts and inspects the content to find threats and block them. It then re-encrypts the content and sends it to the real recipient.”

Technical Deep Dive:

The exhibit shows that the policy is allowing HTTPS and the SSL/SSH inspection profile is certificate-inspection , not deep-inspection . That is the key issue. With certificate inspection, FortiGate can inspect only SSL metadata such as the certificate and SNI/hostname context; it cannot decrypt the HTTPS payload itself. Because EICAR is detected by antivirus through payload inspection, FortiGate must see the file contents. Without deep SSL inspection, the antivirus engine never gets the decrypted payload, so the file can pass even though the antivirus profile is attached.

Option A is incorrect because FortiGate firewall policies often use ACCEPT + security profile enforcement ; the session can still be blocked by antivirus after policy match. Option B is incorrect because web filter is not required for antivirus detection. Option C is incorrect because the real requirement is deep SSL inspection , not specifically proxy-based mode; full SSL inspection is the deciding factor here.

In practice, to block EICAR over HTTPS, you would apply a deep-inspection SSL profile to the policy, for example:

config firewall policy

edit < policy-id >

set inspection-mode flow

set av-profile " default "

set ssl-ssh-profile " deep-inspection "

next

end

On real hardware, this also matters for performance design. Simple firewall/NAT sessions are often NP fast-pathed, but once you enable deep SSL inspection and content scanning, traffic is typically handed to CPU/WAD/content-inspection path for decryption and scanning, so throughput is lower than certificate-inspection or no-inspection.