Technical Tip: How to disable the Link-Local Multicast Name Resolution (LLMNR) in FortiGate.

Link-Local Multicast Name Resolution is the protocol that allows IPv4 and IPv6 hosts on a local network to resolve each other's names without using a DNS server.

LLMNR runs on the local network segment and uses multicast packets for name resolution for neighbor hosts.
It is primarily utilized where, by tradition, DNS resolution is either unavailable or it would be impracticable to have it done. For example, a small local network or one unreachable by DNS servers.

Disable the Link-Local Multicast Name Resolution in the FortiGate CLI:

config system interface

    edit <interface name>
        set netbios-forward disable

     end

Note:

The netbios-forward is also used to forward the NetBIOS requests to the WINS server.

Related article:

Technical Note: Forwarding NetBIOS requests