Changed NSE5_FSW_AD-7.6 Exam Questions

According to theFortiSwitchOS 7.6 Administration Guideand theFortiSwitch 7.6 Study Guide, Dynamic ARP Inspection (DAI) is a security feature used to intercept, log, and discard ARP packets with invalid IP-to-MAC address bindings. DAI is primarily used to prevent " Man-in-the-Middle " attacks, such as ARP spoofing or ARP cache poisoning.

In this scenario, DAI is active on VLAN 10. When DAI is enabled, the FortiSwitch intercepts all ARP packets on untrusted ports and validates them against a trusted source—most commonly theDHCP snooping database. As shown in the " DHCP Snooping database " exhibit, PC2 is correctly mapped to IP 10.0.10.30 and MAC 00:09:0F:AB:00:0B.

When PC2 attempts to send a forged ARP reply claiming that IP 10.0.10.254 (the FortiGate ' s IP) is located at its own MAC address (00:09:0F:AB:00:0B), the FortiSwitch ' s DAI engine inspects the packet. It checks the DHCP snooping database for a binding that matches IP 10.0.10.254 to MAC 00:09:0F:AB:00:0B. Finding no such valid entry (because the database correctly identifies the MAC 00:09:0F:AB:00:0B as belonging to IP 10.0.10.30), the switch identifies the ARP packet as illegitimate.

Consequently, the FortiSwitch willdrop the ARP repliesbecause they fail the DAI validation check against the established DHCP snooping bindings. Option A is incorrect as DAI functions independently of IPSG once the database is populated. Option B is incorrect because " accepting " the spoofed packet is the opposite of DAI ' s purpose. Option C is incorrect because DAI is specifically designed to run on untrusted ports to protect the network from client-side attacks.

According to theFortiSwitchOS 7.6 Administration Guide (Page 320), management traffic on a FortiSwitch is associated with a specific logical interface, which in this case is the " internal " interface. The exhibit shows that the " internal " interface is configured onVLAN 4094(both as native and allowed). This means that for any management traffic (such as HTTPS, SSH, or SNMP) to reach the switch CPU, it must be able to traverse the physical uplink on VLAN 4094.

However, the configuration forport24(the uplink) is currently restricted. It is set withnative VLAN 100and an allowed-vlans list that only includes100 and 200. Because VLAN 4094 is not included in the allowed list of port24, all frames belonging to the management VLAN (4094) are dropped by the switch ' s ingress/egress filters on the uplink.

To resolve this and restore management access, the administrator has two valid configuration paths based on the provided options:

Option B:Change thenative VLAN on port24 to VLAN 4094. By making 4094 the native VLAN, untagged management traffic can traverse the port, effectively allowing the " internal " interface to communicate with the network.

Option D:Add VLAN 4094 to the allowed VLANs on port24. This ensures that VLAN 4094 is no longer filtered out, allowing management frames to pass through the uplink while maintaining the current native VLAN for other traffic.

Option C is irrelevant as removing a working VLAN (200) does not help the management traffic. While Option A describes an alternate architectural approach (moving management into an already-allowed VLAN), Options B and D represent the direct fixes for the mismatch described in the 7.6 administration documentation.

In mixed-vendor network environments, such as deployments that include bothFortiSwitchandCiscodevices, properLayer 2 discovery protocolsmust be enabled to allow devices to automatically discover neighbors and exchange essential device and interface information. FortiSwitchOS 7.6 supports bothCisco Discovery Protocol (CDP)andLink Layer Discovery Protocol (LLDP)to ensure interoperability.

Cisco Discovery Protocol (CDP)is a Cisco-proprietary Layer 2 discovery protocol widely used by Cisco switches, routers, and IP phones. When CDP is enabled on FortiSwitch interfaces, Cisco devices can discover FortiSwitch neighbors and receive information such as device ID, port ID, platform, and capabilities. This is particularly important in Cisco-centric networks where CDP is the primary discovery mechanism.

Link Layer Discovery Protocol (LLDP), defined by IEEE 802.1AB, is a vendor-neutral discovery protocol supported by both Fortinet and Cisco devices. Enabling LLDP allows FortiSwitch and Cisco devices to exchange standardized information including system name, port description, VLAN information, and management address. LLDP is essential for cross-vendor compatibility and is commonly enabled by default in modern enterprise networks.

The remaining options are incorrect.Unidirectional Link Detection (UDLD)is used to detect unidirectional fiber or copper link failures and does not provide device discovery or information exchange.LLDP-MEDis an extension of LLDP specifically designed for media endpoints such as IP phones and is not required for general switch-to-switch discovery.

Therefore, to ensure automatic discovery and information exchange between FortiSwitch and Cisco devices,both CDP and LLDP must be enabled, makingOptions B and Cthe correct and fully verified answers based on FortiSwitchOS 7.6 documentation.

According to theFortiSwitchOS 7.6 Administration Guideand theFortiSwitch 7.6 Study Guide, the Routing Information Base (RIB) contains all potential routes discovered by the switch, but theForwarding Information Base (FIB)only includes the " best " active routes used for hardware packet forwarding. When the routing process receives multiple paths to the exact same destination (in this case, the default route 0.0.0.0/0), it must select the most reliable source based on a specific hierarchy.

The primary tie-breaker for routes from different protocols is theAdministrative Distance (AD). AD is a value from 1 to 255 that represents the trustworthiness of the routing source, where alower value is more preferred. In the provided exhibit:

TheOSPFroute has an AD of110(shown as [110/10]).

TheStaticroute has been configured with an AD of220(shown as [220/0]).

Because the OSPF route ' s AD (110) is lower than the Static route ' s AD (220), the system considers the OSPF route to be superior. Consequently, only the OSPF route is " Selected " and installed into theFIB. The static route remains in the RIB as a " backup " or floating static route; it will only be moved to the FIB if the preferred OSPF route becomes unavailable. Option D is incorrect because having identical prefixes is not a " conflict " but a standard part of route selection where AD decides the winner. Option A is incorrect because metric is only compared if the AD is identical.