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

“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.

In FortiOS 7.6, when FortiGate is integrated with FortiAnalyzer and FortiManager, firewall policies rely on a Universally Unique Identifier (UUID) to ensure proper policy tracking, synchronization, and log correlation across devices.

Why the UUID is required

Every firewall policy in FortiOS has a UUID.

FortiManager uses the UUID to:

Track policies across managed FortiGate devices

Maintain policy consistency during installs and revisions

FortiAnalyzer uses the UUID to:

Correlate logs accurately to the correct firewall policy

Preserve log association even if policy order or policy ID changes

Without a UUID:

Policy-to-log mapping can break

FortiManager cannot reliably manage or synchronize policies

FortiAnalyzer log analysis becomes inconsistent

This is explicitly documented in Fortinet administration and logging architecture references.

Why the other options are incorrect

B. Policy IDPolicy ID can change when policies are moved and is not reliable for long-term correlation across FortiManager and FortiAnalyzer.

C. Sequence IDSequence ID reflects GUI ordering only and has no role in log correlation.

D. Log IDLog ID is generated per log event, not per firewall policy.

Phase 1 being up confirms the two FortiGate devices can authenticate and build the IKE SA. Phase 2 failing indicates the IPsec (Quick Mode) SA negotiation is failing due to mismatched Phase 2 parameters.

From the exhibit, the Phase 2 mismatches that would prevent SA establishment are:

1) Phase 2 selectors must mirror each other (Proxy IDs)

HQ-NGFW Phase 2 selector shows:

Local: 10.0.11.0/24

Remote: 172.20.1.0/24

BR1-FGT Phase 2 selector shows:

Local: 172.20.1.0/24

Remote: 10.11.0.0/24 ⟵ does not match HQ’s local subnet (10.0.11.0/24)

In FortiOS, Phase 2 comes up only when the peers’ selectors (proxy IDs) match as opposite pairs (local on one side = remote on the other).

✅ Fix: A. On BR1-FGT, set Remote Address to 10.0.11.0/255.255.255.0.

2) Phase 2 proposal must match (encryption/authentication)

HQ-NGFW shows encryption AES128 (with SHA1)

BR1-FGT shows encryption AES256 (with SHA1)

For Phase 2 to establish, both peers must have at least one common proposal (same encryption and authentication settings). With one side set to AES128 and the other to AES256, there is no match.

✅ Fix: D. On HQ-NGFW, set Encryption to AES256.

Why the other options are not correct

B. Enable Diffie-Hellman Group 2: The exhibit’s mismatch is not resolved by adding DH group 2, and DH group must match when PFS is enabled. This option does not align the peers based on what’s shown.

C. Set Seconds to 43200: Phase 2 lifetime mismatches typically do not prevent Phase 2 from coming up (the negotiated lifetime can be adjusted by the peers). The hard blockers here are the selectors and proposal mismatch.

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 FortiOS, there are three main components of web filtering:

• Web content filtering...

• URL filtering: uses URLs and URL patterns to block or exempt web pages from specific sources ...

• FortiGuard Web Filtering service...”

“In the web filter profile, Fortiguard category filtering enhances the web filter features. Rather than block or allow websites individually, it looks at the category that a website has been rated with. Then, FortiGate takes action based on that category, not based on the URL.”

“If you consider that a particular URL does not have the correct category, you can ask to re-evaluate the rating in the Fortinet URL Rating Submission website. You can also override a web rating for an exceptional URL in the FortiGate configuration. ”

“Static URL filtering is another web filter feature, which provides more granularity. Configured URLs in the URL filter are checked from top to bottom against the visited websites. If FortiGate finds a match, it applies the configured action.”

“To find the exact match, URL filtering has three pattern types: Simple, Regular Expressions, and Wildcard .”

“So, with these different features, what is the inspection order? If you have enabled many of them, the inspection order flows as follows:

The local static URL filter

FortiGuard category filtering...”

Technical Deep Dive:

The correct answers are A and B .

A is correct because a static URL filter gives per-URL granularity. Since the category Freeware and Software Downloads is currently allowed in the profile, adding a local static URL filter entry for download.com with Block lets FortiGate deny only that site while continuing to allow the rest of the category. This also aligns with the documented inspection order, where the local static URL filter is checked before FortiGuard category filtering .

B is also correct because a web rating override can reclassify a specific exceptional URL. If download.com is re-rated into a blocked category such as Malicious Websites , it will be blocked by the profile while other sites in Freeware and Software Downloads remain allowed.

Why the others are wrong:

C is not the intended web-filter solution. A firewall policy with an FQDN object operates at policy/routing resolution level, not as a category-aware web filtering exception.

D is wrong because changing the whole category to Warning affects all sites in that category, not just download.com.

In production, the cleaner design is usually: keep the category allowed, then add a local URL-filter exception or a web-rating override for the specific site . For HTTPS traffic, remember FortiGate still needs enough SSL inspection visibility to identify the hostname correctly. A representative CLI approach for URL filtering is:

config webfilter urlfilter

edit 1

config entries

edit 1

set url " download.com "

set type wildcard

set action block

next

end

next

end

This is the most deterministic way to block one site without penalizing the rest of the category.

“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.

In FortiOS 7.6, SD-WAN Performance SLAs are used to measure link quality and influence SD-WAN rule decisions. The following three statements are true.

C. All the SLA targets can be configured.

True

SD-WAN Performance SLAs allow administrators to configure:

Latency

Jitter

Packet loss

Mean Opinion Score (MOS) (for voice)

Threshold values for these metrics are fully configurable per SLA.

This is explicitly documented in the SD-WAN Performance SLA configuration section.

D. They are applied in an SD-WAN rule lowest cost strategy.

True

Performance SLAs are commonly used with the Lowest Cost (SLA-based) strategy.

In this strategy:

FortiGate selects the lowest-cost link that meets the SLA requirements.

If a link violates the SLA, it is excluded from selection.

E. They can be measured actively or passively.

True

FortiOS supports:

Active probing (synthetic probes such as ping/HTTP)

Passive measurement (based on real traffic statistics)

Administrators can choose how SLAs are measured depending on the deployment and requirements.

Why the other options are incorrect

A. They rely on session loss and jitter.

Incorrect

SLAs measure packet loss, latency, and jitter.

Session loss is not an SLA metric in FortiOS.

B. They monitor the state of the FortiGate device.

Incorrect

Performance SLAs monitor link quality, not FortiGate system health or device state.

According to the FortiOS 7.6 Administrator Study Guide and official documentation, SD-WAN rules (services) determine the path selection for traffic matching specific criteria. Version 7.6 provides specific flexibility regarding how these strategies handle multiple member interfaces.

First, Manual with load balancing (Statement B) is a valid configuration. In the Manual strategy, the administrator orders interfaces by preference, but by enabling the Load balancing toggle, the FortiGate can distribute traffic across all members that are up.

Second, the Lowest Cost (SLA) strategy has been enhanced to support two modes. When the load balancing option is disabled, it acts as Lowest Cost (SLA) without load balancing (Statement A), selecting the single lowest-cost link that meets the SLA. Alternatively, by enabling the toggle, it functions as Lowest Cost (SLA) with load balancing (Statement D), where the FortiGate distributes traffic across all interfaces that satisfy the SLA target, regardless of their individual costs.

Statements C and E are incorrect because " Lowest Quality " is not a recognized SD-WAN strategy, and the Best Quality strategy is specifically a priority-based selection for a single " best " link, meaning the load balancing toggle is not available in the GUI when this mode is selected.

From the exhibits:

A VIP named VIP-WEB-SERVER is configured on WAN (port2) with:

External IP: 100.65.0.200

Mapped (internal) IP: 10.0.11.50

Port forwarding enabled (TCP)

External service port: 443

Map to IPv4 port: 4443

The inbound firewall policy Web_Server_Access is:

From WAN (port2) to LAN (port4)

Destination: VIP-WEB-SERVER

Service: HTTPS

NAT: Disabled (meaning no source NAT is applied)

What happens to the packet

A host 100.65.1.111 sends TCP SYN dst-port 443 to 100.65.0.200.

When FortiGate matches the VIP and forwards traffic to the internal server, FortiGate performs destination NAT (DNAT) based on the VIP:

Source IP is unchanged because policy NAT is disabled:

Source remains 100.65.1.111

Destination IP is translated by the VIP:

Destination becomes 10.0.11.50

Destination port is translated by the VIP port-forward:

Destination port becomes 4443

Therefore, at the time FortiGate forwards the packet to the destination (internal server), it will be:

Source address: 100.65.1.111

Destination address: 10.0.11.50

Destination port: 4443

“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.

Based on the FortiOS 7.6 Authentication and User Group documentation, the correct answer is A.

Meaning of “Include in every user group” (FortiOS 7.6)

When configuring a RADIUS server on FortiGate, enabling Include in every user group has a very specific and documented effect:

The configured RADIUS server object is automatically added to all FortiGate user groups.

As a result, any user who successfully authenticates against that RADIUS server becomes a valid member of every FortiGate user group, unless additional group filtering (such as RADIUS attributes) is applied.

This simplifies configuration when the same external authentication source must be accepted across multiple firewall policies that reference different user groups.

This behavior is explicitly described in the FortiOS 7.6 Administrator Guide under RADIUS authentication servers and user groups.

Why Option A is Correct

FortiGate user groups can include:

Local users

LDAP servers

RADIUS servers

Enabling Include in every user group causes FortiGate to:

Insert the RADIUS server into all existing and future FortiGate user groups

Therefore, all users authenticating via this RADIUS server are implicitly allowed in every FortiGate user group.

This is exactly what option A describes.

Why the Other Options Are Incorrect

B: FortiGate does not push users or groups into the RADIUS server. Authentication is always initiated by FortiGate toward RADIUS.

C: FortiGate does not manage or modify RADIUS-side group definitions.

D: LDAP and RADIUS user groups are separate authentication mechanisms; this setting does not merge or affect LDAP groups.

Based on the FortiOS 7.6 Infrastructure and IPsec VPN documentation, Dead Peer Detection (DPD) can be configured in three primary modes: On Demand, On Idle, and Disabled.

On Demand (Default Mode): This mode is specifically designed to minimize unnecessary traffic. In this mode, FortiGate sends DPD probes only when there is no inbound traffic but the FortiGate is attempting to send outbound traffic. Because network communication is typically bidirectional, the absence of inbound traffic while outbound traffic is being sent is a primary indicator of a potentially dead tunnel. This matches the specific requirement described in the question.

On Idle: In this mode, DPD probes are sent if no traffic (neither inbound nor outbound) has been observed in the tunnel for a specific period. It verifies the tunnel status even when the connection is completely idle.

Enabled: In older versions or specific CLI contexts, " Enabled " may refer to periodic DPD, but in the current FortiOS 7.x/7.6 GUI and CLI terminology for Phase 1 settings, the active modes are defined as on-demand or on-idle.

Disabled: In this mode, the FortiGate does not send DPD probes but will still respond to DPD probes sent by the remote peer.

The requirement that the administrator wants probes sent only when there is no inbound traffic (usually implying the FortiGate is sending but not receiving) is the fundamental definition of the On Demand mechanism in the Fortinet curriculum.

“As previously stated, collector agent-based polling mode has three methods (or options) for collecting login information. The order on the slide from left to right shows most recommend to least recommended:

• WMI ...

• WinSecLog ...

• NetAPI ...”

Technical Deep Dive:

The correct three AD polling methods are WMI, WinSecLog, and NetAPI . These are the collector-agent polling options FortiGate FSSO uses against Windows domain controllers. WMI is generally the most efficient because the DC returns requested login events directly. WinSecLog polls Windows Security Event Logs and is typically more reliable than NetAPI for not missing recorded logons. NetAPI can be faster, but it is more prone to missing events under load because it depends on temporary session information rather than persistent security logs.

Why the other options are wrong:

DNS reverse lookup is not one of the three AD polling methods. DNS is used by FSSO to resolve workstation names to IP addresses and to track IP changes, but it is not itself a polling method for collecting AD logon events. FSSO REST API is also not one of the documented collector-agent AD polling methods in the study guide.

From an operational standpoint, FSSO login collection and workstation verification are separate functions. The collector agent may still rely on DNS and workstation checks after a login is learned, but the actual AD polling methods remain only WMI, WinSecLog, and NetAPI . On a FortiGate, when troubleshooting FSSO behavior, you would typically validate the collector feed and user cache with commands such as:

diagnose debug authd fsso list

diagnose debug authd fsso server-status

Those commands help confirm whether the users gathered by the collector through one of those three polling methods are reaching FortiGate correctly.

“After the IPS engine examines the traffic stream for a signature match, FortiGate scans packets for matches, in this order, for the application control profile:

1. Application and filter overrides ...”

“Because application overrides are applied first in the scan, these two applications are allowed and generate logs.”

“The priority in which application and filter overrides are placed takes precedence.”

Technical Deep Dive:

The correct answer is C. Application and Filter Overrides .

If you already set the P2P category to Block , but some peer-to-peer traffic is still being allowed, the first thing to check is whether there is an application override or filter override that matches that traffic before the category action is applied. FortiGate processes Application and Filter Overrides before Categories , so any matching override set to Allow or Monitor will effectively bypass the category block.

Why the others are wrong:

A only affects user-facing block-page behavior for HTTP/HTTPS applications, not whether P2P is blocked.

B is for enforcing expected services on expected ports and for blocking applications on non-default ports. It is not the first place to look when a category block is being bypassed.

D concerns web categorization, not application-control category enforcement.

Operationally, this is a classic troubleshooting sequence: first inspect the override table , then the category action , then logs under Application Control to see which signature and action actually matched.

From the exhibits:

The Application Control sensor has these key settings:

Application and Filter Overrides

Priority 1: Excessive-Bandwidth (Type: Filter) with Action Block

Priority 2: Google (Type: Filter) with Action Monitor

Category actions shown include Social Media set to Block (this category includes Facebook).

The firewall policy is using:

Flow-based inspection

Application control enabled (profile: default)

Deep inspection enabled (helps identify applications inside HTTPS)

Logging enabled

FortiOS applies Application Control as follows (top-down within the Application Control profile):

Overrides are evaluated by priority (highest priority first).

The first matching override determines the action (block/monitor/allow) for that traffic.

Category-based actions apply to applications that fall into those categories unless an override matches first.

Why A is correct

A. YouTube access is blocked based on Excessive-Bandwidth Application and Filter override settings.

The profile explicitly blocks the Excessive-Bandwidth behavior filter at the highest override priority.

When YouTube traffic is detected as matching the Excessive-Bandwidth behavior, FortiGate will apply the Block action due to the override.

Because this is a priority override, it is enforced before lower-priority entries.

Why B is correct

B. Facebook access is blocked based on the category filter settings.

The Application Sensor shows Social Media configured with a Block action.

Facebook is categorized under Social Media, so it will be blocked when matched by Application Control.

Why C is not correct

C. Facebook access is allowed but you cannot play Facebook videos...

Since the Social Media category is set to Block, Facebook would be blocked at the category level (not merely video playback).

Why D is not correct

D. YouTube search is allowed based on the Google override...

The Google override action is Monitor, not Allow.

“Monitor” logs/detects but does not override a block condition to “allow” traffic.

Also, YouTube traffic is not guaranteed to be treated as “Google” in a way that would permit it, and any matching block condition (such as Excessive-Bandwidth) would still take precedence.

“You can configure the fail-open setting under config ips global to control how the IPS engine behaves when the IPS socket buffer is full .”

“If the IPS engine does not have enough memory to build more sessions , the fail-open setting determines whether the FortiGate should drop the sessions or bypass the sessions without inspection .”

“It is important to understand that the IPS fail-open setting is not just for conserve mode—it kicks in whenever IPS fails. Most failures are due to a high CPU issue or a high memory (conserve mode) issue.”

Technical Deep Dive:

The correct answer is A .

The log text says:

logdesc= " IPS session scan paused "

action= " drop "

msg= " IPS session scan, enter fail open mode "

That combination indicates an IPS failure condition , specifically the condition described in the guide where the IPS socket buffer is full and the IPS engine lacks enough memory/resources to build additional sessions. In that state, FortiGate applies the configured IPS fail-open behavior . Since the log shows action= " drop " , the device is not bypassing those new sessions; it is dropping them.

Why the other choices are wrong:

B is wrong because the guide ties fail-open to socket buffer/resource exhaustion , not packet decode failure.

C is wrong because this is not evidence of a manual diagnostic pause.

D is wrong because the study guide does not associate this log with dirty-flag packet reevaluation.

Operationally, this usually points to high memory , high CPU , or conserve-mode pressure affecting the IPS engine. Useful checks are:

get system performance status

diagnose hardware sysinfo conserve

diagnose sys top

Those help confirm whether the IPS issue is being driven by memory pressure or CPU exhaustion.

“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.

NetAPI: Polls temporary sessions created on the DC when a user logs on or logs off and calls the NetSessionEnum function on Windows. It’s faster than the WinSec and WMI methods; however, it can miss some logon events if a DC is under heavy system load. This is because sessions can be quickly created and purged form RAM, before the agent has a chance to poll and notify FG.

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.