Fortinet Updated NSE4_FGT_AD-7.6 Exam Questions and Answers by lily-may

“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.

A closely related routing principle from the guide is:

“For each session, FortiGate performs two route lookups... After completing these two lookups, FortiGate writes the routing information to its session table. Subsequent packets are routed according to the session table, not the routing table.”

Also, the guide notes an HA limitation that helps explain the same design principle for FortiGate-terminated sessions:

“Enabling session pickup allows active sessions to be seamlessly handed picked up by the new primary in the event of an HA failover... Note that there are some limitations to this – for example, any sessions that terminate at the FortiGate itself ( e.g. SSL VPN, proxy sessions ) cannot be handed off to another FortiGate and must be restarted on the new primary.”

Technical Deep Dive:

The correct answer is D .

In multi-WAN environments, session preservation is used so that traffic for sessions that are tightly bound to the FortiGate interface they terminate on—most notably SSL VPN and other FortiGate-terminated flows—does not suddenly switch to another egress interface just because the routing table changes. Those sessions are sensitive to interface consistency. If replies start leaving through a different WAN after a route recalculation, the remote peer may see an address/interface mismatch and the session can break.

That means:

A is the opposite of session preservation. Preservation is meant to avoid moving active sessions around.

B is not the purpose of the feature.

C is unrelated.

D correctly describes why an administrator would enable it.

Operationally, this matters most for SSL VPN , management-plane flows, and other sessions that terminate on the FortiGate itself , not just ordinary transit traffic. Transit sessions are generally tracked in the session table and can often survive normal routing behavior more gracefully, but FortiGate-terminated sessions are much more sensitive to WAN/interface changes.

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

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

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

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

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

Technical Deep Dive:

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

green = 82

red = 88

extreme = 89

Because memory usage is 90% , it is:

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

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

That makes A and D correct.

Why the others are wrong:

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

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

A useful verification command is:

diagnose hardware sysinfo conserve

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

From the exhibits:

The firewall policy has NAT enabled and is configured to Use Dynamic IP Pool.

The selected IP pool (Internet-pool) is configured as:

Type: One-to-One

External IP Range: 100.65.0.110–100.65.0.111 (only two public IPs)

PC1 and PC2 can access the internet because each one-to-one NAT mapping consumes one public IP from the pool. When PC3 is added, there is no third public IP available in the pool, so FortiGate cannot allocate a one-to-one mapping for PC3 and the session fails.

FortiOS behavior here is standard: with one-to-one IP pools, the available pool size limits how many distinct internal sources can be translated concurrently (depending on allocation and sessions), and a pool with only two IPs will not reliably support three separate hosts needing translations.

Therefore, the administrator can fix this in two valid ways:

B. In the IP pool configuration, set end ip to 100.65.0.112.

This expands the pool by adding an additional public IP address, making three public IPs available (.110, .111, .112), so PC3 can be assigned an address for one-to-one NAT.

D. In the IP pool configuration, set type to overload.

Changing the pool type to overload enables PAT (many-to-one), allowing multiple internal hosts (PC1, PC2, PC3) to share the pool address(es) using different source ports. This removes the “one public IP per internal host” limitation inherent to one-to-one pools.

Why the other options are not correct:

A. Multiple Interface Policies is unrelated to IP pool exhaustion and does not solve NAT allocation limits.

C. match-vip affects VIP matching behavior for destination NAT/virtual IP usage and does not address the source NAT pool shortage causing PC3 to fail.