NSE 7 Network Security Architect NSE7_FSN_AR-7.6 Passing Score

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 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 correct answer is D. Assertion dump.

The study guide states that: “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.”

It also shows the real-time SAML debug output under “** Assertion Dump ****”**, where the SAML attributes appear inside the assertion, such as:

< saml:Attribute Name= " username " >

< saml:Attribute Name= " groups " >

The same study-guide page explicitly labels this area as “Attributes sent by IdP”

So, although the IdP sends an authentication response overall, the actual section that contains the SAML attributes is the Assertion dump

The correct answer is D.

The study guide explains that IKEv2 has two initial exchanges:

IKE_SA_INIT

IKE_AUTH

and then later exchanges such as:

CREATE_CHILD_SA

It also states the roles of those exchanges:

IKE_SA_INIT negotiates the security settings for IKE traffic

IKE_AUTH performs mutual authentication and sets up the piggyback child SA

CREATE_CHILD_SA creates a new child SA or rekeys an existing child SA

Most importantly, the study guide explicitly says:

“By IKEv2 design, no Diffie-Hellman public key is exchanged during an IKE_AUTH exchange. Consequently, any phase 2 Diffie-Hellman group configuration mismatch between FortiGate and the peer is experienced only during the first rekey (CREATE_CHILD_SA exchange) of the child SA created during IKE_AUTH.”

This proves the key idea behind the question: an IKEv2 tunnel can come up successfully first, then fail later during a CREATE_CHILD_SA rekey/renegotiation event because of a phase 2 mismatch. Among the provided options, the matching later-stage cause is mismatched quick-mode selectors during CREATE_CHILD_SA.

Why the other options are wrong:

A is wrong because if the proposal mismatch were in the initial negotiation path, the tunnel would fail during establishment, not after it was already up. The study guide places initial tunnel establishment in IKE_SA_INIT and IKE_AUTH

B is wrong because a mismatch in IKE_SA_INIT affects the initial establishment stage, not a tunnel that was already brought up successfully

C is wrong because a pre-shared key mismatch is part of authentication during IKE_AUTH, so the tunnel would not come up successfully in the first place