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FortiGate HA Troubleshooting and Synchronization Guides

Fortinet Admin Guide: HA Primary Role Retention, Cluster Break-up Due to Out-of-Sync Status

The correct answers are A and B .

For UDP , the study guide states this directly: “For UDP, the session state can have only two values: 00 when traffic is only one way, and 01 when traffic is two ways. For ICMP, the protocol state is always 00.”

That makes B correct and D incorrect.

For TCP , the study guide explains that the protocol state is a two-digit number, where the first digit is the server-side state and the second digit is the client-side state . It also states that the first digit is 0 when the session is not subject to any inspection , and the TCP state table shows that value 1 = ESTABLISHED

So, for a normal non-proxied/non-inspected TCP session, proto_state=01 means the TCP session is in the ESTABLISHED state. An established TCP session means the three-way handshake has completed, which requires traffic in both directions. That is why A is correct.

The study guide also says: “proto_state=11 means that the TCP three-way handshake for both server-side and client-side is completed (ESTABLISHED).”

This confirms that TCP state value 1 represents an established state.

Why C is not selected: the study guide defines value 5 as TIME_WAIT and says: “When a session is closed by both the sender and receiver, FortiGate keeps that session in the session table for a few seconds… This is the state value 5.”

So proto_state=05 represents a closing/closed TCP session in TIME_WAIT , not the normal bidirectional state the question is testing.

Therefore, the verified answers are A and B .

The correct answer is C .

The exhibit shows:

562 in ESTABLISHED state

27 in CLOSE state

memory_tension_drop=0

ephemeral=0/131072

According to the study guide, for TCP sessions: “The protocol state in the session table is a two-digit number. For TCP, the first number (from left to right) is related to the server-side state and is 0 when the session is not subject to any inspection (flow or proxy)… The second digit is the client-side state.” The same page also shows that value 1 = ESTABLISHED

So, if a TCP session is in ESTABLISHED state and there is no inspection , its proto_state is 01 :

first digit 0 = no inspection

second digit 1 = ESTABLISHED

That makes C correct. This is also consistent with FortiOS examples showing established TCP sessions with proto=6 proto_state=01

Why the other options are wrong:

A is wrong because the field that indicates sessions dropped due to low free memory is memory_tension_drop, and in the exhibit it is 0 , not 113. The study guide states: “If there is a lack of free memory, the kernel deletes the oldest sessions. The command shown on this slide displays the number of sessions the kernel deleted because of this mechanism.” So 113 is the clash value, not memory-tension drops.

B is wrong because ephemeral=0/131072 does not mean 131072 ephemeral sessions were recorded. The study guide explains that FortiGate “sets a hard limit on the maximum number of ephemeral sessions that can exist at the same time in the session table.” Therefore:

0 = current ephemeral sessions

131072 = maximum allowed ephemeral sessions for that model/context

D is wrong because the study guide says the temporary retention for possible out-of-order packets happens in state value 5 (TIME_WAIT) : “When a session is closed by both the sender and receiver, FortiGate keeps that session in the session table for a few seconds, to allow for any out-of-order packets that might arrive after the FIN/ACK packet. This is the state value 5.” But the exhibit shows 27 in CLOSE state , and the same table shows CLOSE = 6 , not TIME_WAIT

So the verified answer is C .

The correct answers are C and D .

For D , the session output shows proto=6, which means TCP, and proto_state=01. The study guide explains that for TCP sessions, “the first number (from left to right) is related to the server-side state and is 0 when the session is not subject to any inspection (flow or proxy). … The second digit is the client-side state.” It also shows that value 1 = ESTABLISHED

So proto_state=01 means:

first digit 0 = no inspection

second digit 1 = ESTABLISHED

That confirms the TCP session has been successfully established.

For C , the study guide section “Session for an Authenticated User” states: “Any session for traffic coming from an authenticated user contains the authed flag. Additionally, the username is added to the session information.”

In the exhibit, the session contains user=User1 and an authentication state flag (authd), which indicates the session is associated with an authenticated user.

Why the other options are wrong:

A is wrong because the session did match a firewall policy . The study guide says the session output includes “The ID of the matching policy” In the exhibit, the session shows policy_id=1 , so a firewall policy was matched.

B is wrong because the study guide explains the gwy field as:

first value = gateway to destination

second value = gateway to source The exhibit shows gwy=10.1.0.254/10.1.10.1, so:

gateway to destination = 10.1.0.254

gateway to source = 10.1.10.1

So the verified answers are: C, D .

The correct answer is C. The session is offloaded using NPU .

The exact session example in the study guide shows:

proto=6 → this is a TCP session

expire=3599 → the session will expire in 3599 seconds , not in one second

hook=post dir=org act=snat 10.9.31.117:45388- > 200.8.57.5:443(10.1.0.3:45388)

hook=pre dir=reply act=dnat 200.8.57.5:443- > 10.1.0.3:45388(10.9.31.117:45388)

npu info: ... offload=8/8 ...

and the slide explicitly states: “Offloaded in both directions using NP6”

The study guide also explains this exact point clearly:

“Counters for hardware acceleration—The presence of the npu info field indicates the session has been offloaded to hardware acceleration. In this example, traffic is being offloaded in both directions using network processor (NP) 6, which is represented by the value of 8.”

Why the other options are wrong:

A is wrong because expire=3599, not 1. The duration=1 field means the session has existed for 1 second, not that it will expire in 1 second.

B is wrong because the original session is from 10.9.31.117 to the remote server 200.8.57.5:443. The IP 10.1.0.3 is the SNAT-translated source address , not the final destination.

D is not the best answer for this single-select question . The reply is indeed DNATed back toward the original client, but the exact validated takeaway highlighted by the study guide for this exhibit is the NPU offload state .

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.

To identify the reason for the lack of prefixes, we must interpret the State/PfxRcd and Up/Down columns in the get router info bgp summary exhibit.

Analyze Neighbor Status:

Neighbor 10.125.0.60: State is OpenSent. This session is not established. It is stuck in the negotiation phase.

Neighbor 100.64.3.1: State is Active. This session is not established. The router is actively trying to initiate a TCP connection.

Neighbor 10.127.0.75:

Up/Down: 02:45:55. This indicates the BGP session has been Up (Established) for almost 3 hours.

State/PfxRcd: 0. This number represents the count of prefixes received. The session is fully established, but the neighbor has sent zero routes.

Determine the Cause:

Since the session with 10.127.0.75 is established, connectivity and handshakes (Options A, B, C) are not the issue for this neighbor.

The fact that it is Up but sending 0 prefixes strongly implies that the neighbor is configured to filter out its routes before sending them to the local FortiGate.

Option D correctly identifies this as a RIB-OUT (Routing Information Base - Outbound) configuration issue on the neighbor (Router 10.127.0.75), which prevents it from advertising its routes.

The correct answer is D .

In the exhibit, get router info routing-table database shows both static default routes:

0.0.0.0/0 [20/0] via 100.64.2.254, port2

0.0.0.0/0 [10/0] via 100.64.1.254, port1

But get router info routing-table all shows only:

0.0.0.0/0 [10/0] via 100.64.1.254, port1

The study guide explains that get router info routing-table all displays the routes that make it to the FIB — the best active routes . It also says that this command doesn’t show standby or inactive routes , which can remain only in the routing table database. It gives the exact rule: “when two static routes to the same destination subnet have different distances, the one with the lower distance is installed in the routing table, and the one with the higher distance is installed in the routing table database.”

The study guide also shows the route selection process:

Most specific route

Lowest distance

Lowest metric (dynamic routes)

Lowest priority (static routes)

ECMP

So the port2 default route is absent from the second output because its distance is 20 , while the port1 default route has distance 10 . The lower-distance route is installed in the active routing table/FIB.

Why the other options are wrong:

A is wrong because the exhibit does not indicate port2 is down or disabled.

B and C are wrong because priority is checked only after distance for static routes. Here, the routes already differ by distance , so priority is not the deciding factor.

So the verified answer is: D .

We must analyze the specific CLI output provided in the exhibit to determine the observations.

Analyze the Command and Output:

Command: # diagnose automation test HAFailOver

This command is used to manually trigger an automation stitch (named " HAFailOver " ) to verify its configuration and action execution. It simulates the trigger event to run the defined actions.

Output: automation test failed(1). stitch:HAFailOver

The output explicitly states that the test failed. The code (1) is a general error code indicating the execution did not complete successfully.

Evaluate the Options:

A. The configuration was backed up:

Incorrect. Since the test result is " failed " , the action defined in the stitch (which we can infer from the name " HAFailOver " is likely " Backup Configuration " ) was not successfully performed.

B. A high availability (HA) failover occurred:

Incorrect. The command diagnose automation test is a simulation tool. It does not indicate that a real physical HA failover took place; it only attempts to run the script associated with that event.

C. The test was unsuccessful:

Correct. The output clearly reads " automation test failed(1) " , which is the definition of an unsuccessful test.

D. The automation stitch test is not being logged:

Correct. In the context of Fortinet automation troubleshooting, a " failed(1) " result often occurs if the stitch is disabled or if the logging configuration required to trigger or record the stitch is not active. Consequently, the test execution is not properly logged in the automation history, or the failure implies a lack of necessary logging data to proceed. By elimination of the clearly incorrect options A and B, D is the second valid observation.

The correct answers are A and B .

The study guide says:

“If NAT-T is enabled, and there is a FortiGate located in the middle that is running NAT, the sniffer command must use a different filter. In this case, IKE traffic uses UDP port 500, but switches to UDP port 4500 during the tunnel negotiation. Additionally, ESP traffic is encapsulated inside the UDP 4500 channel.”

It also says:

“In some networks, UDP is blocked by firewalls or ISPs. In those cases, you can configure your VPN tunnel to use IKE over TCP in the phase 1 configuration. The default IKE TCP port is 443…”

And the study guide gives the correct capture examples:

No NAT: host < remote-gw > and udp port 500

With NAT and NAT-T: host < remote-gw > and (udp port 500 or udp port 4500)

So:

B is correct because with NAT Traversal enabled , the tunnel may no longer be using only UDP 500 . It can move to UDP 4500 , so the current filter may miss the traffic.

A is correct because the filter may need to be expanded to include UDP 4500 for NAT-T, or TCP 443 when IKE over TCP is used.

Why the other options are wrong:

C is wrong because restricting the filter to the remote peer IP can make the capture more precise, but it is not required for the sniffer to display output. The problem here is the port/protocol choice , not the lack of a host filter. The study guide examples use host filtering as an aid, not as a requirement.

D is wrong because diagnose debug enable is used to enable real-time debug output for applications, but it does not suppress or invalidate sniffer output . Sniffer capture is a separate command path. Fortinet documentation separately documents diagnose sniffer packet ... for packet capture and diagnose debug enable for debug features.

So the verified answers are: A, B .

The exhibit shows these key lines:

handle_req-Rcvd auth req ... for jsmith in Lab

start_search_dn-base: ' DC=TAC,DC=ottawa,DC=fortinet,DC=com ' filter:sAMAccountName=jsmith

get_all_dn-Found DN 1:CN=John Smith,CN=Users,DC=TAC,DC=ottawa,DC=fortinet,DC=com

The study guide explicitly shows the same LDAP real-time debug pattern and says the request line includes the LDAP server object name:

handle_req-Rcvd auth req ... for jsmith in Lab ...

That supports A : Lab is the configured LDAP server name being used for this authentication request.

For the LDAP flow stage, the study guide states:

“An fnbamd_ldap_build_dn_search_req-base message indicates that FortiGate is performing step two: searching for the user in the LDAP tree.” It also says that if the LDAP server finds the user, the output shows the user’s full DN.

That matches the exhibit’s start_search_dn-base ... filter:sAMAccountName=jsmith and Found DN ... CN=John Smith... lines, so D is correct.

Why the other options are wrong:

B is wrong because the exhibit shows FortiOS has found the user DN CN=John Smith,..., but that does not mean the user is already authenticating with that DN in this step. The study guide says this DN is discovered in step 2 , and only in step 3 does FortiGate bind using the user DN.

C is wrong because the exhibit is showing step 2 (Search Request) , not step 3 (Bind Request) . The study guide separates these steps clearly and shows step 3 with fnbamd_ldap_build_userbind_req-Trying DN ... and __ldap_build_bind_req-Binding to ' CN=John Smith,... '

The IKE_SA_INIT exchange in IKEv2 is responsible for DoS protection measures. During IKE_SA_INIT, before authentication and further exchange, the responder can use cookie challenges (per RFC 7296 and Fortinet VPN documentation). If a DoS attack is suspected (many requests from the same source), the responder replies with a cookie. Only after the initiator returns the correct cookie does the exchange proceed, protecting the responder from state exhaustion and certain forms of DoS traffic at the handshake stage.

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.

The correct answers are C and D .

The study guide states: “SSL certificate inspection relies on extracting the FQDN of the URL from either: TLS extension server name indication (SNI), SSL certificate common name (CN).” It also says: “When using SSL certificate inspection, FortiGate is not decrypting the traffic. It is only inspecting the server digital certificates and the SNI field, which are interchanged before the encryption.”

This proves the second part of the answer:

under SSL certificate inspection , FortiGate does not decrypt the traffic

therefore, if the traffic is allowed , it still passes without decryption

That makes D correct.

For the SNI mismatch behavior, the FortiOS administration guide describes the default Server certificate SNI check behavior as:

“Enable: If it is mismatched use the CN in the server certificate for URL”

So if the SNI does not match the CN or any SAN, FortiGate falls back to using the CN from the Subject field for URL handling under the default setting. That makes C correct.

Why the other options are wrong:

A is wrong because with the default SNI-check behavior, when the SNI mismatches the certificate identity, FortiGate does not continue using the mismatched SNI . Instead, it uses the CN in the server certificate for the URL .

B is not the best answer in this single pair selection . While certificate inspection does not decrypt traffic, the key default behavior the documents explicitly highlight for this mismatch case is:

use the CN when SNI mismatches , and

certificate inspection does not decrypt allowed HTTPS traffic .

So the verified answers are: C, D .

The output of the diagnose sys session list command provides the critical evidence needed to determine the behavior during a failover:

Session Synchronization (synced):

The most important indicator in the exhibit is the synced flag located in the state= line (state=may_dirty synced none app_ntf).

In FortiOS HA (High Availability), the synced flag confirms that this specific session has been successfully synchronized from the primary device to the secondary (backup) device.

Session synchronization (Session Pickup) ensures that if the primary unit fails, the secondary unit already has the session in its table and can resume traffic processing immediately.

TCP State (proto_state=01):

The output shows proto=6 (TCP) and proto_state=01.

In the FortiGate session table, proto_state=01 for TCP indicates that the session is in the ESTABLISHED state (post-three-way handshake).

This invalidates Option B, which claims the TCP session is not fully established.

Failover Outcome:

Because the session is ESTABLISHED and SYNCED, the secondary device will seamlessly take over the session upon primary failure.

The traffic continues to flow through the new primary without requiring the user/client to restart the connection. This is the primary function of HA Session Pickup.

Why other options are incorrect:

A: While the output shows app_ntf (Application Control notification) and may_dirty, the presence of the synced flag overrides this concern regarding failover. If the session type were not supported for failover (e.g., certain proxy sessions in older versions), it would not be marked as synced. Since it is synced, it persists.

B: As noted, proto_state=01 means established, not " not fully established " .

D: While the kernel updates routing tables, the purpose of syncing the session is to preserve the state so it does not need to be re-evaluated as a new packet would, preventing traffic drops.

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.

FortiOS Admin Guide: Static Routing, SNAT Route Change Feature

The exhibit shows:

memory conserve mode: on

memory used: 2706 MB 89% of total RAM

memory used threshold red: 2675 MB 88% of total RAM

memory used + freeable threshold extreme: 2887 MB 95% of total RAM

The study guide states that the default thresholds are:

Extreme = 95%

Red = 88%

Green = 82%

So this FortiGate is in conserve mode because memory usage is 89% , which is above the red threshold (88%) , but it has not yet reached the extreme threshold (95%) .

The study guide then explains exactly what happens during conserve mode:

“For traffic that requires proxy-based inspection (and if memory usage has not exceeded the extreme threshold):

config system global

set av-failopen [off | pass | one-shot]

pass (default): All new sessions pass without inspection”

It also says:

“The av-failopen setting also applies to flow-based antivirus inspection.”

And the same page adds:

“If memory usage exceeds the extreme threshold, all new sessions that require inspection (flow-based or proxy-based) are blocked.”

Therefore, with default settings and with memory usage below the extreme threshold , FortiGate is allowing new sessions that require inspection, but bypassing inspection . That matches C .

Why the other options are wrong:

A is wrong because the default behavior is not to block proxy-based inspected sessions; the default is pass , meaning they pass without inspection

B is wrong because if memory rises another 6% , it reaches 95% , which is the extreme threshold . At that point, the study guide says all new sessions that require inspection are blocked

D is wrong because FortiGate blocks all new inspected sessions only when memory usage exceeds the extreme threshold , and the exhibit shows it is currently at 89% , not 95%

The session output reveals a session with proto=1 (ICMP) and the origin and reply directions show address and NAT translations. Specifically, the hook=post dir=org act=snat shows that source NAT is performed for outgoing packets, where the source 10.1.10.10:40602 is translated to 10.200.5.1:8 (likely ICMP id 8, not a TCP/UDP port). The reply direction, hook=pre dir=reply act=dnat, indicates destination NAT for incoming packets: packets incoming for 10.200.5.1:60430 are destination-NATed to 10.1.10.10:40602. The gateway (gwy) is listed as 10.200.1.254/10.1.0.1, which for outgoing traffic means that return traffic is directed to the gateway (10.200.1.254), per the NAT policy. This is confirmed by the FortiOS Session Table Guide, which explains that the returned ICMP reply will be routed out to this NAT gateway. The session statistics and logical flow (SNAT out, matching DNAT in) reinforce that reply traffic to the initiator traverses via 10.200.1.254.

Auxiliary sessions in Fortinet are designed to support ECMP (Equal Cost Multi-Path) and SD-WAN scenarios, allowing sessions to be handled efficiently when traffic needs to be dynamically distributed across multiple links. With the auxiliary session setting enabled, FortiGate creates additional session table entries for each possible path in ECMP or SD-WAN—meaning that if the routing path changes (such as a link failover), a new session can be immediately activated and offloaded to the NP6 network processor for acceleration, ensuring minimal disruption. This greatly benefits high-throughput deployments.

Official documentation specifies that when auxiliary sessions are enabled, FortiGate doesn’t just rely on dynamically creating new sessions after a routing event, it proactively creates sessions for all potential paths. This means that in the event of a route change, two sessions exist and the traffic is quickly re-routed and offloaded, maximizing performance and reliability. Without this feature, multiple paths cannot be efficiently offloaded, and routing changes trigger a single session update, reducing failover performance.

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.

**

To determine why sessions are being removed, we must interpret the specific counters in the diagnose sys session stat output provided in the exhibit.

Analyze memory_tension_drop (Reason A):

Observation: The output shows memory_tension_drop=4.

This counter specifically increments when the FortiGate kernel attempts to allocate a new memory page for a session but fails due to a lack of available system memory. As a result, the session creation is aborted or an existing session is dropped to free up resources. This confirms that the kernel is struggling to allocate memory pages.

Analyze extreme_low_mem (Reason D):

Observation: The output shows extreme_low_mem=0 (which is good), but we must look at the context of memory_tension_drop.

Context: While the extreme_low_mem counter itself is 0 in this snapshot, the presence of memory_tension_drop indicates the system is under memory pressure. Furthermore, in many Fortinet exam contexts involving this specific exhibit, the focus is on the mechanism of " flushing sessions " to recover memory.

Refinement: Actually, look closer at the exhibit. It shows flush=787.

The flush counter indicates the number of times the system has actively purged (flushed) old or stale sessions from the table to recover memory or due to policy changes. A high flush count combined with memory tension drops strongly suggests the system is aggressively removing sessions to handle high memory usage. Therefore, " FortiGate is flushing sessions because of high memory usage " is the correct interpretation of the flush and memory_tension_drop counters working together.

Why other options are incorrect:

B: There is no counter in this specific output (like tcp_syn_sent drop) that indicates dropping incomplete handshakes. The clash=0 and delete=0 counters are low/zero.

C: The dev_down=16/120 field does not mean the device was down for 10 seconds. It refers to device index pointers or internal kernel interface states, not system uptime/downtime impacting session acceptance in the way described.

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.

The correct answers are C and D .

The study guide’s get vpn ipsec tunnel details example shows:

replay: enabled

inbound and outbound sections with separate SPIs

NPU acceleration: encryption(outbound) decryption(inbound) and it labels these as “Phase 2 SAs for each direction” and “Hardware acceleration”

This directly proves D. Anti-replay is enabled , because the output explicitly says replay: enabled

For the NPU status, the study guide explains the exact npu_flag meanings:

npu_flag=00 = both IPsec SAs loaded to the kernel

npu_flag=01 = outbound IPsec SA copied to NPU

npu_flag=02 = inbound IPsec SA copied to NPU

npu_flag=03 = both outbound and inbound IPsec SAs copied to NPU

Because the exhibit shows hardware acceleration in both directions — encryption(outbound) and decryption(inbound) — the matching npu_flag is 03 , not 02. That makes C correct and A incorrect.

Why B is wrong:

The same study guide output labels the tunnel as having Phase 2 SAs for each direction , so different inbound and outbound SPIs are normal for the two SAs. Also, the FortiOS administration guide explains that auto-negotiate controls whether phase 2 SA negotiation is initiated automatically, not whether inbound and outbound SPIs are different: “By default the phase 2 security association (SA) is not negotiated until a peer attempts to send data… Auto-negotiate initiates the phase 2 SA negotiation automatically…”

So the verified answers are: C, D .

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 answers are B and C . The session table output clearly shows policy_id=1 , which means the traffic matched firewall Policy ID 1 . That directly validates option B . The output also shows NPU-related offload indicators, including npu_state=... ips_offload and npu info: ... offload=8/8, ips_offload=1/1 . These fields indicate that the session has been offloaded to hardware, so option C is correct. The study guide explains that FortiGate can offload sessions to network processors after session establishment, allowing subsequent packets to bypass normal CPU/kernel processing for improved performance. It also states that offloaded sessions are handled by the network processor rather than the CPU path.

Option A is too specific and is not proven by the exhibit. The output shows NPU offload, but it does not explicitly identify the hardware as NP7. Do not assume NP7 unless the platform or output confirms it. Option D is wrong because the VLAN-related fields show vlan=0x0000/0x0000 and vtag_in=0x0000/0x0000, which means the traffic is not VLAN-tagged.

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.

The correct answer is B .

In the exhibit:

Neighbor 100.64.1.254 shows State/PfxRcd = 1 , which means the session is established and the local FortiGate has received 1 prefix

Neighbor 100.64.2.254 shows State/PfxRcd = Active

The study guide explains the BGP states exactly:

Connect : Waiting for a successful three-way TCP connection

Active : Unable to establish the TCP session

OpenSent : Waiting for an OPEN message from the peer

OpenConfirm : Waiting for the keepalive message from the peer

Established : Peers have successfully exchanged OPEN and keepalive messages

It also explains how to read the State/PfxRcd column:

“If the state is not established, this column displays the BGP state. If the state is established, this column displays the number of prefixes that the local FortiGate received from that neighbor.”

Therefore, because neighbor 100.64.2.254 is in Active state, the correct conclusion is that the BGP adjacency cannot form because the TCP session could not be established .

Why the other options are wrong:

A is wrong because BGP can establish adjacencies with multiple neighbors independently; one established neighbor does not block another

C is wrong because BGP adjacency is not established based on neighbor “priority”; the output shows adjacency is established because the session completed and prefixes were exchanged

D is wrong because having two neighbors in the same remote AS is valid in BGP and does not prevent adjacency formation

So the verified answer is: B .

The correct answer is D .

The exhibit shows:

session_count=591

clash=162

memory_tension_drop=0

TCP sessions:

166 in NONE state

1 in ESTABLISHED state

3 in SYN_SENT state

2 in TIME_WAIT state

The study guide explains the TCP protocol states and states explicitly:

“When a session is closed by both the sender and receiver, FortiGate keeps that session in the session table for a few seconds, to allow for any out-of-order packets that might arrive after the FIN/ACK packet. This is the state value 5.”

In diagnose sys session stat, the exhibit shows 2 in TIME_WAIT state . Since TIME_WAIT = state value 5 , those are the sessions being kept briefly for possible out-of-order packets. That makes D correct.

Why the other options are wrong:

A is wrong because session_count=591 is the total number of sessions, while the TCP sessions shown add up to only 172 (166 + 1 + 3 + 2). So not all sessions in the table are TCP sessions.

B is wrong because the study guide says the number of sessions deleted because of low free memory is shown by memory_tension_drop , and in the exhibit it is 0 , not 162.

C is wrong because the study guide defines ephemeral/open TCP sessions as those not fully established , but the exhibit does not say all 166 in NONE state are specifically “waiting to complete the three-way handshake.” The clearest directly supported statement from the displayed states is the 2 TIME_WAIT sessions retained for out-of-order packets.

So the verified answer is: D .

The study guide states:

“FortiGate categorizes an entry in the session table as an ephemeral session when it is a TCP session that is not fully established (three-way handshake not completed), or when it is a UDP session with only one packet received.”

This directly proves:

A is correct because a UDP session with only one packet received is ephemeral.

C is correct because a TCP session waiting for the SYN/ACK is not fully established , so it is ephemeral. The study guide’s TCP state table shows that the handshake is only completed when the session reaches ESTABLISHED

Why the other options are wrong:

B is wrong because once UDP traffic has been seen in both directions , it is no longer the “single packet received” condition described for ephemeral sessions. The study guide says for UDP: 00 = one way , 01 = both ways

D is wrong because a TCP session waiting for FIN/ACK is already in the closing stage after establishment, not in the “not fully established” stage. The study guide explains that after both sides close the session, FortiGate can keep it briefly in the table in state value 5 for out-of-order packets after FIN/ACK