FCSS_NST_SE-7.6 Sample Questions Answers

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 .

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 administrator is running a packet sniffer with the filter ' udp port 500 or udp port 4500 or esp ' . The result is " no output, " even though the VPN is attempting to establish (failing).

A. The VPN is configured to use IKE over TCP:

Standard IPsec IKE negotiation uses UDP port 500 (IKE) and UDP port 4500 (NAT-T).

However, if IKEv2 over TCP (RFC 8229) or Fortinet ' s proprietary IKE over TCP is configured (often used to bypass firewalls that block UDP), the traffic will use TCP (often port 4500 or 443).

The sniffer filter explicitly looks for udp or esp (IP Protocol 50).

If the traffic is encapsulated in TCP, it matches tcp protocol, not udp or esp (raw ESP). Therefore, the sniffer sees zero packets matching the filter.

Why other options are incorrect:

B: esp is a valid argument for diagnose sniffer packet. It is equivalent to filtering for IP protocol 50.

C: If the ISP were blocking traffic, the sniffer (running on the local FortiGate) would still see the outbound packets generated by the FortiGate trying to initiate the connection. " No output " implies the local device isn ' t even generating packets matching that filter.

D: Mismatched IKE versions would still generate IKE negotiation packets (proposals/errors) that would be captured by the sniffer.

According to the official Fortinet documentation (Technical Tip: Useful FSSO Commands), heartbeat messages play a crucial role in communication between the FSSO Collector Agent and FortiGate. These messages are regularly sent from the Collector Agent to verify its status, maintain session awareness, and confirm connectivity between the authentication infrastructure and FortiGate appliances.

Option B is confirmed by Fortinet, as the collector agent logs on Windows or its management console will specifically note heartbeat events, connection status, and any issues maintaining contact with FortiGate units.

Option C is validated by both official CLI documentation and the technical tip linked. On FortiGate, heartbeat messages from the collector agent are visible using real-time debug tools such as diagnose debug application authd or FSSO-specific commands. These enable administrators to monitor live logon states, session status, and connection health directly from the FortiGate CLI. The debug stream shows heartbeats received and their effect on active logons, associating health monitoring with active sessions.

Heartbeat operation is fully automated once FSSO is set up—there is no requirement for manual enablement or configuration, aligning with Fortinet’s philosophy of seamless integration and centralized management across the Security Fabric. This ensures that both FortiGate and the collector agent can quickly and reliably detect any miscommunication or outage, addressing authentication issues proactively.

The correct answer is D .

The study guide shows the ipsmonitor test usage exactly:

1: Display IPS engine information

2: Toggle IPS engine enable/disable status

5: Toggle bypass status

99: Restart all IPS engines and monitor

So diagnose test application ipsmonitor 5 is used to toggle bypass status , which corresponds to enabling IPS bypass mode .

Why the other options are wrong:

A is wrong because disabling the IPS engine is option 2 , not 5.

B is wrong because the study guide does not define option 5 as IPS session information.

C is wrong because restarting all IPS engines and monitors is option 99 , not 5.

So the verified answer is: D .

The correct answer is B. Assertion dump .

The study guide states: “SAML attributes are pieces of information about a user that are exchanged between IdPs and SPs during the SAML authentication process. These attributes are included in the SAML assertion, which is built by the IdP as part of the authentication process.”

The same study guide page for real-time SAML troubleshooting shows the section labeled **** Assertion Dump **** , and inside that assertion it displays the actual user attributes, such as:

< saml:Attribute Name= " username " >

< saml:Attribute Name= " groups " >

It also explicitly marks this part as “Attributes sent by IdP”

Why the other options are wrong:

A. Bindings HTTP post is incorrect because bindings define how SAML messages are transported , not the section that contains the attributes. The study guide says: “Bindings: Define how SAML protocol messages are transmitted over different communication channels.”

C. Authentication request is incorrect because that is built by the SP and sent toward the IdP, not where the IdP’s user attributes are shown. The study guide’s flow says the SP “Builds auth request” and the IdP later “Builds auth response.”

D. Authentication response is broader than the exact section being asked. The exact section in the study guide where the IdP-provided attributes are shown is the Assertion dump .

So the verified answer is: B .

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

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

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

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

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

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

The command on this slide shows a summary of the statuses of all the OSPF neighbors. For each neighbor, it displays the adjacency state and if it is a DR, a BDR, or neither (DROther) Pagina 362 Enterprise_Firewall_7.2_Study. - Point-to-point networks contain only two peers, one at each end of a point-to-point link - Broadcast networks (multi-access) support more than two attached routers. They also support sending messages to multiple recipients (broadcasting). Pagina 365 Enterprise_Firewall_7.2_Study. In any multi-access network there is one DR and one BDR. Pagina 439 Network_Security_Support_Engineer_7.4_Study FULL/- This represents a point-to-point network

The diagnose debug authd fsso server command is the primary tool for troubleshooting communication between the FortiGate and the FSSO Collector Agent. This debug output reveals the status of the connection and the reasons for failure. The three most common connectivity issues identified by this debug are:

FortiGate cannot reach the IP address of the collector agent (Option C): The debug will show connection timeouts or " host unreachable " errors if the Layer 3 connectivity is missing.

The connection was refused / Port mismatch (Option B): If the FortiGate can reach the IP but the Collector Agent is not listening on the specified port (default 8000), the debug will display " Connection refused. " This often happens if the port configured on the FortiGate does not match the listening port on the agent.

The pre-shared key does not match (Option D): If the IP and Port are correct, the next step is authentication. If the password configured on the FortiGate does not match the one on the Collector Agent, the debug will explicitly show an " Authentication failed " or " password mismatch " error during the handshake.

Note on other options: Option A (SSL) is less common than basic connectivity/auth mismatches. Option E (Group filters) relates to user processing logic, which occurs after connectivity is established.

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

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 get router info bgp summary output lists BGP neighbor status:

Prefix Reception: The " State/PfxRcd " column shows the number of prefixes received from the neighbor—neighbor 100.64.1.254 has " 1 " , confirming option A.

Received Message Count: Under " MsgRcvd " , 18 packets have been received from neighbor 100.64.1.254. This matches option C.

The second neighbor 100.64.2.254 is in " Active " state and has received/sent 0 packets, indicating that its TCP connection is NOT established, disproving option B.

There is no indication anywhere that the router is " still calculating " prefixes; " Active " just means no session is established, so option D is incorrect.

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.

To determine the path the traffic will take, we must look at the FortiGate Route Lookup Precedence (Packet Processing Flow) and the specific configurations shown in the exhibit

Analyze the Routing Precedence:

In FortiOS, when a packet arrives (and is not part of an existing session), the FortiGate performs route lookups in a specific order:

Policy Routes: Configured under config router policy (or diagnose firewall proute list). These are checked first. If a packet matches the criteria (Source, Destination, Protocol, Incoming Interface), the Policy Route is used immediately, bypassing the standard routing table.

FIB (Forwarding Information Base): If no Policy Route matches, the device looks at the standard routing table (Static, Connected, Dynamic).

Analyze the Exhibit:

Policy Route Section: The output of diagnose firewall proute list shows an active policy route (id=1).

Destination: 100.65.0.0/255.255.255.0 (Matches the network in the question).

Action: It directs traffic to gateway 10.0.4.253 via oif=6(port4).

Routing Table Section: The output of get router info routing-table database shows multiple routes for 100.65.0.0/24 (Static, OSPF, BGP) all with distance 10. The Static route (S) is currently selected (* > ) in the FIB.

Conclusion:

Because Policy Routes take precedence over the standard routing table (FIB), the FortiGate will forward the traffic using the instructions in Policy Route ID 1. It will not use the Static, BGP, or OSPF routes visible in the routing table for any traffic that matches the policy route ' s criteria (ingress port 3).

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 Internet Key Exchange version 2 (IKEv2) protocol simplifies the negotiation process compared to IKEv1. It is defined by a specific sequence of message exchanges to establish a secure IPsec tunnel.

The correct chronological order of the IKEv2 exchanges is:

IKE_SA_INIT (Initial Exchange):

This is the first exchange. It negotiates the security parameters for the IKE Security Association (IKE SA), sends nonces, and performs the Diffie-Hellman key exchange. At the end of this exchange, the communication is encrypted, but the peers are not yet authenticated.

IKE_AUTH (Authentication Exchange):

This is the second exchange. It authenticates the previous messages, exchanges identities and certificates (if used), and establishes the first Child SA (the actual IPsec Security Association used for data traffic).

CREATE_CHILD_SA (Subsequent Exchanges):

This exchange occurs after the IKE SA and the initial Child SA are established. It is used to create additional Child SAs (for different traffic selectors) or to perform re-keying for the IKE SA or existing Child SAs.

Why other options are incorrect:

A & B: Incorrect because CREATE_CHILD_SA cannot happen before the SA is initialized (IKE_SA_INIT) and authenticated (IKE_AUTH).

D: Incorrect because IKE_AUTH cannot occur before IKE_SA_INIT.

Therefore, the protocol flow is IKE_SA_INIT $\rightarrow$ IKE_AUTH $\rightarrow$ CREATE_CHILD_SA.

The correct answer is D. IKE_AUTH .

The study guide explicitly states:

“IKE_Auth exchange:

• Performs the mutual authentication of two IKE endpoints.

• Configures settings like IP/mask, DNS, and so on.

• Sets up the piggyback of a child SA. Negotiates IP flow and security settings for the IPsec SA.”

It also says:

“By default, a piggyback child (IPsec) SA is negotiated along with the IKEv2 SA during IKE_AUTH. If additional IPsec SAs are needed … they are negotiated during subsequent CREATE_CHILD_SA exchanges.”

Why the other options are wrong:

A. IKE_SA_INIT is incorrect because this exchange negotiates the security settings to protect the IKE traffic, not the first CHILD_SA.

B. INFORMATIONAL is incorrect because it is used to convey control messages between IKE endpoints.

C. CREATE_CHILD_SA is incorrect for the first CHILD_SA, because it is used to create new additional child SAs or rekey existing ones after the initial exchange.

The debug flow message iprope_in_check() check failed, drop specifically indicates a failure in the Local-In Policy check. The " iprope " (IP ROouting Policy Enforcement) engine handles policy lookups. The _in_check suffix confirms that the decision is regarding traffic destined to the FortiGate itself (Local-In traffic), rather than traffic passing through it.

D. The packet was dropped because the requested service is not enabled on FortiGate:

This is the most common cause. When a packet arrives destined for the FortiGate ' s interface IP (e.g., an HTTPS or SSH request), the kernel checks if that specific service is enabled in the interface settings (set allowaccess). If the service is not enabled (e.g., trying to Ping an interface where PING access is disabled), the iprope_in_check function fails and drops the packet immediately.

C. The packet was dropped because the trusted host list is misconfigured:

Even if the service (e.g., HTTPS) is enabled on the interface, the FortiGate checks the Administrator settings. If Trusted Hosts are configured, the source IP of the incoming packet is compared against the allowed list. If the IP is not on the list, the Local-In policy check (iprope_in_check) fails, and the packet is dropped to secure the management plane.

Why other options are incorrect:

A: If traffic is dropped by a standard Firewall Policy (traffic passing through the device from one interface to another), the debug message will typically state denied by policy x or no matching policy. It would generally be a forward check (iprope_fwd_check or similar), not an _in_check.

B: If there is no route to the source, the error is a Reverse Path Forwarding (RPF) failure. The debug flow logs this explicitly as reverse path check fail, drop.

The correct answers are C, D, and E .

The study guide lists the exact OSPF adjacency requirements :

“Interfaces of peers are the same type and in the same OSPF area”

“Each peer has a unique router ID”

“OSPF authentication, if enabled, is successful”

These map directly to:

C. OSPF interface network types match

D. Authentication settings match

E. OSPF router IDs are unique

The same study-guide slide also states other requirements such as:

peers’ primary IPs must be in the same subnet with the same mask

hello and dead intervals must match

OSPF MTUs must match

Why the other options are wrong:

A is wrong because link cost matching is not listed as an adjacency requirement . OSPF cost affects path selection, not whether adjacency can form.

B is wrong because interface priority does not need to be unique . Priority is used for DR/BDR election, where the highest priority wins, and ties are broken by router ID.

So the verified answers are: C, D, E .

The correct answers are A and D .

The debug output shows:

Sent RADIUS req to server ' RadiusServer ' : IP=172.25.188.164 ... user= " student " using CHAP

Result for radius svr ' RadiusServer ' 172.25.188.164(0) is 0

Sending result 0 for req 2

The study guide explains that in RADIUS real-time debug, FortiGate shows the IP address of the RADIUS server it is querying. In the example, it says FortiGate “creates an access request to the RADIUS server at IP address 10.0.13.130” and shows the line Sent radius req to server ... IP=10.0.13.130

So in your exhibit, the queried server is clearly 172.25.188.164 , which makes A correct.

The study guide also states:

“The message fnbamd_comm_send_result-Sending result 0 indicates that the authentication was successful and that FortiGate received the Access-Accept message.”

Since your exhibit also ends with Sending result 0 , that makes D correct.

Why the other options are wrong:

B is wrong because result 0 means authentication successful , not failed

C is wrong because the debug explicitly shows using CHAP , and the study guide lists supported RADIUS schemes as CHAP, PAP, MS-CHAP, and MS-CHAPv2

E is wrong because the study guide says two-factor authentication would involve an Access-Challenge response: “If two-factor authentication is enabled on the server, the response is an Access-Challenge message” Your exhibit shows successful result 0 / Access-Accept , not a challenge.

So the verified answers are: A, D .

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 .

In the provided session table output, the following details justify the answers:

Policy ID Match: The line policy_id=1 directly confirms that this session was matched by Firewall Policy ID 1. According to Fortinet’s session table documentation, the policy_id field always references the policy that allowed this session, so this is a clear indicator.

Session Offloading: The presence of the strings npu_state, ips_offload, and notably the NPU info section such as offload=8/8, ips_offload=1/1 shows that this session has been offloaded to the Network Processor Unit (NPU). Fortinet technical documentation states that " offload " values greater than zero in both directions (and an NPU info section) affirm that NPU hardware processing (fast path) is handling this traffic, thus the session is not being handled in software only.

Other options:

VLAN Tagging (vlan=0x0000/0x0000): This means no VLAN tag is assigned to this session.

NP7: The actual NPU model handling the session isn’t exposed in this snippet–the offload parameters shown are generic and not specific to NP7 hardware, so it cannot be concluded from the session data.

Based on the Fortinet FCSS - Network Security 7.6 documents and the analysis of the VPN tunnel exhibit, here is the verified answer.

Questions no: 91

Verified Answer: A, C

Comprehensive and Detailed Explanation with all FCSS - Network Security 7.6 documents:

To determine the status of the VPN tunnel, we must examine the specific counters and fields in the diagnose vpn tunnel list output provided in the exhibit.

Analyze Phase 2 Status (Option A):

The output displays child_num=0.

In IKEv2 (and IKEv1 implementations in FortiOS), " Child SAs " refer to the Phase 2 (IPsec) Security Associations that carry the actual data traffic.

A value of 0 indicates that no Phase 2 tunnels are established. If Phase 2 were up, child_num would be at least 1.

Additionally, under the proxyid section, the field sa=0 confirms there is no active Security Association for that traffic selector.

Analyze Traffic Status (Option C):

The stat line shows: rxp=0 txp=0 rxb=0 txb=0.

rxp (Received Packets) and txp (Transmitted Packets) are both zero. This definitively confirms that no traffic is traversing the tunnel currently. This is expected since Phase 2 is down.

Analyze Phase 1 Status (Why B is incorrect):

The tunnel entry exists in the list with a valid tun_id, and NAT-Traversal is active (natt: mode=keepalive).

The presence of the tunnel in this command output, along with active Keepalive mechanisms, typically indicates that Phase 1 (IKE SA) is established and the peers are communicating on port 4500 (NAT-T), even though the data tunnels (Phase 2) failed to negotiate. If Phase 1 were down, the tunnel would often not appear in this " list " view or would show different status flags indicating a complete connection failure.

Conclusion: The exhibit shows a scenario where the Phase 1 control channel is likely up (evidenced by the entry existence and NATT keepalives), but the Phase 2 data channel is down (child_num=0), resulting in zero traffic flow (rxp=0/txp=0).

The correct answers are A and C .

The exhibit shows that preserve-session-route is enabled on port1:

config system interface

edit " port1 "

set preserve-session-route enable

next

end

The study guide explains the effect of this setting exactly:

“enable: FortiGate marks existing session routing information as persistent, and applies only the modified routes to new sessions”

It also states:

“The current route must still be present in the FIB. Otherwise, FortiGate flags the session as dirty and reevaluates it”

And the same page further clarifies:

“If you enable this setting, sessions passing through that interface continue to pass without being affected by the routing changes. The routing changes apply only to new sessions. If the route is removed from the FIB, then FortiGate must flag the session as dirty, flush its gateway information, and reevaluate the session.”

This proves:

A is correct because with preserve-session-route enable, existing sessions are normally preserved and routing changes apply only to new sessions.

C is correct because the session remains unchanged unless the current route is removed from the FIB/routing table, in which case FortiGate dirties and reevaluates the session.

Why the other options are wrong:

B is wrong because when the active route is removed, FortiGate does not simply mark the session dirty and stop there. The study guide says it “flags the session as dirty and reevaluates it” , which means route lookup happens again.

D is wrong because the session does change if the active route is removed. FortiGate flushes gateway information and reevaluates the session.

So the verified answers are: A, C .

The correct answer is B .

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

That directly proves B .

Why the other options are wrong:

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

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

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