Refer to the exhibit, which shows a LAN interface connected from FortiGate to two FortiSwitch devices. https://kxbjsyuhceggsyvxdkof.supabase.co/storage/v1/object/public/file-images/Fortinet_FCSS_EFW_AD-7.6/page_32_img_1.jpg What two conclusions can you draw from the corresponding LAN interface? (Choose two.)

The LAN interface must use a 802.3ad type interface.

B/C make sense here. The interface needs to be 802.3ad (B) for aggregation and FortiLink is used to centrally manage VLANs (C). Not seeing any SD-WAN or STP requirement in this context. Anyone disagree?

Pretty sure it's B and C, saw a similar question on a practice exam. Matches the 802.3ad and FortiLink setup.

Question 15 - Fortinet FCSS_EFW_AD-7.6 Real Exam Questions [Jan 2026 Update]

Q: 15

Refer to the exhibit, which shows a LAN interface connected from FortiGate to two FortiSwitch devices.

What two conclusions can you draw from the corresponding LAN interface? (Choose two.)

Options

Correct Answer:

B, C

Explanation

The exhibit shows a FortiGate connected to a pair of FortiSwitch devices using a single logical interface. This topology represents a Multi-Chassis Link Aggregation (MCLAG) configuration, which provides link and device redundancy.

To connect to an MCLAG peer group, the FortiGate must use a Link Aggregation Group (LAG) interface, which is standardized as IEEE 802.3ad. This bundles the physical links to each switch into one logical interface.

This integrated deployment is managed using FortiLink, where the 802.3ad aggregate interface on the FortiGate is configured as the FortiLink interface. This allows the FortiGate to act as the switch controller, centrally managing the FortiSwitch units and provisioning VLANs across the switched network.

Why Incorrect

A. MCLAG is specifically designed to provide a loop-free, active-active topology, making Spanning Tree Protocol (STP) on the aggregate links unnecessary.

D. SD-WAN is a feature for aggregating and managing multiple Wide Area Network (WAN) links for internet and private network access, not for LAN-side switch connectivity.

References

1. FortiSwitch—Managed by FortiOS 7.4.0

Administration Guide

Page 51

Section: "FortiLink split interface and MCLAG".

The documentation states: "On the FortiGate unit

you create an 802.3ad aggregate interface with at least two member interfaces." This directly supports that an 802.3ad interface type is required (Answer B).

The same section describes this exact topology as a FortiLink configuration for managing an MCLAG peer group

which includes VLAN management (Answer C).

2. FortiSwitchOS 7.4.0

Administration Guide

Page 183

Section: "Configuring MCLAG".

The guide explains: "MCLAG provides Layer-2 redundancy by preventing the spanning-tree protocol (STP) from blocking the redundant links between the MCLAG peer group and the client network device." This confirms that STP is not the required loop-prevention mechanism (Refutes Answer A).

3. FortiOS 7.4.0

Administration Guide

Page 1789

Section: "SD-WAN".

The guide defines SD-WAN: "SD-WAN simplifies the management of multiple WAN connections...". This confirms SD-WAN is a WAN technology

not used for LAN switch connections (Refutes Answer D).

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