Regarding the scenario where a FortiSwitch did not reboot after the authorization process while the other devices did, the most likely cause, given the configuration settings in the exhibit, is:

The management mode was set to use FortiLink mode (Option B) : If the FortiSwitch was already configured to use FortiLink for its management mode, it may not require a reboot to complete the authorization process as its management interface settings are already aligned with FortiLink requirements. This is unlike switches that might be transitioning from a standalone or another management mode, which would typically require a reboot to apply new management settings fully.

In a multi-tenancy setup on FortiGate, you can assign a FortiSwitch port to a VDOM in two primary ways:

Switch the FortiLink Interface to the Target VDOM (A) : This method involves configuring the FortiLink interface, which is the dedicated interface used to manage FortiSwitch units from FortiGate, to operate within a specific VDOM. This effectively assigns all ports on the FortiSwitch, managed through that FortiLink interface, to the designated VDOM.

Create a Virtual Port Pool on the FortiGate CLI (C) : Virtual port pools are created on FortiGate and allow ports from FortiSwitch to be grouped and assigned to a VDOM. This method is more granular and flexible, as it allows specific ports on the FortiSwitch to be dedicated to different VDOMs without requiring the entire switch or FortiLink interface to be dedicated to a single VDOM.

According to the FortiSwitchOS 7.6 Administration Guide and the FortiSwitch 7.6 Study Guide , the output of the diagnose stp instance list command provides critical information about the Spanning Tree Protocol (STP) state of a switch within a given instance. In the provided exhibit, the output for Instance ID 0 (CST) on Core-2 shows several key indicators of its role and connectivity within the STP topology.

First, the output explicitly identifies a Root bridge with MAC address 02090f000701 and a priority of 4096. Core-2 itself has a MAC address of 02090f000702 and a priority of 32768. Because Core-2 knows the MAC address and priority of the Root bridge, it must have received this information via Bridge Protocol Data Units (BPDUs) . Furthermore, the port table shows that port3 on Core-2 has been assigned the role of ROOT and is in the FORWARDING state. In STP/RSTP, a Root Port is the port on a non-root switch that has the lowest path cost to the root bridge. To elect a Root Port and maintain its state, the switch must continuously receive BPDUs from the root bridge (or a bridge closer to the root) on that port.

Option B is incorrect because Core-2 has a Root Port , which is only present on non-root bridges. Option C is incorrect because ports 1, 2, 4, 5, and the internal port are all in the FORWARDING state. Option D is incorrect as the output does not show any ports in an ALTERNATE role; all active ports are either ROOT or DESIGNATED. Therefore, the most accurate conclusion is that Core-2 has successfully received BPDUs to identify the root and determine its own port roles.

The appearance of a serial number in the Native VLAN column for port23 suggests that the switch connected to this port is identified uniquely in the network. Given the options provided:

A standalone switch with the shown serial number is connected on port23 (Option C) : This is the most plausible explanation. The FortiSwitch configuration interface is displaying the serial number of a standalone switch that is directly connected to port23. This kind of display helps in identifying and managing individual devices in a network setup, especially in environments with multiple switches.

According to the FortiSwitchOS 7.6 Administration Guide and the FortiSwitch 7.6 Study Guide , the interaction between a managed switch and a connected endpoint depends on whether the endpoint can participate in the 802.1X authentication process. When a security policy is applied to a port, the switch sends EAP (Extensible Authentication Protocol) requests to the device to initiate the login.

The FortiSwitch handles two primary failure scenarios differently:

Non-supplicant (No 802.1X Support): If a device, such as a legacy PC or a basic printer, does not have an 802.1X supplicant, it will not respond to the switch's EAP requests. In this case, the switch waits for the duration specified in the Guest authentication delay field (30 seconds in the exhibit). Once this timer expires without a response, the switch places the device into the Guest VLAN . As shown in the exhibit, the Guest VLAN is explicitly set to "onboarding.fortilink (onboarding)" .

Authentication Failure: If a device does support 802.1X but the user provides incorrect credentials, the RADIUS server returns an Access-Reject message. In this scenario, the device is moved to the Authentication fail VLAN , which the exhibit identifies as "quarantine.fortilink (quarantine)" .

Note: Because MAC authentication bypass (MAB) is disabled in the exhibit, the switch will not attempt to authenticate the device's MAC address against the RADIUS server before defaulting to the Guest VLAN. Therefore, for any device lacking an 802.1X supplicant, the result is placement into the onboarding VLAN.

According to the FortiSwitchOS 7.6 Administration Guide and the FortiSwitch 7.6 Study Guide , Internet Group Management Protocol (IGMP) snooping is a Layer 2 mechanism that allows a switch to "listen" to IGMP conversations between hosts and routers to maintain a map of which ports require specific multicast streams. When IGMP snooping is enabled, the switch populates a Multicast Layer 2 Forwarding Table (as shown in the exhibit), which ensures that multicast traffic is only forwarded to ports where a receiver has explicitly requested it (e.g., PC1 on port1).

When IGMP snooping is disabled , the switch no longer maintains this granular forwarding table. By default, a Layer 2 switch that is not performing IGMP snooping treats multicast traffic as if it were broadcast traffic . Consequently, instead of being intelligently forwarded only to the interested receiver (PC1), the multicast traffic for group 225.1.2.3 will be flooded to all ports within the same VLAN (VLAN 10). This means PC2, even if it has not joined the group, will receive the multicast packets at the physical layer, leading to unnecessary bandwidth consumption and increased CPU load on unintended recipients.

The documentation explicitly states that disabling IGMP snooping reverts the switch to a "flood-all" behavior for multicast frames within the broadcast domain. Option A is incorrect because the host (PC1) remains a member of the group; only the switch's forwarding logic changes. Option B is incorrect as the switch may still see the messages but will not act on them to prune ports. Option D is incorrect as disabling the feature removes the prune/stop mechanism, causing traffic to flow everywhere rather than stopping.

FortiSwitch supports packet capture through various methods, but the Sniffer profile is specifically capable of capturing traffic on both trunks and management interfaces. Here's why:

Sniffer Profile (B):

Versatile Capture: The sniffer profile in FortiSwitch is designed to capture traffic across different types of interfaces, including trunks (where multiple VLANs are present) and management interfaces (used for controlling and monitoring the switch).

Configuration Flexibility: You can configure sniffer profiles to target specific traffic, offering flexibility in monitoring and troubleshooting network issues on both data and management planes.

Other Options:

SPAN (A) is used mainly for mirroring traffic to another port for analysis but is typically limited in its ability to capture management interface traffic.

sFlow (C) and TCP dump (D) are useful tools but do not specifically align with the capability to universally capture traffic across trunks and management interfaces in the context described.