LLMNR multicast slow down network service

  • Hi.

    I manage a network with ~300 hosts with PFSense, latelly the internet connection is working intermitent, i tested and the channel is stable.
    So we checked and see many LLMNR multicast petitions from many machines.

    We decided to disable the LLMNR in the windows machines, but there's a lot of hosts with windows but is a large process, with pfSense is possible to deny LLMNR in the network?


  • Banned

    No, because the multicast traffic does not go through the router.

  • LAYER 8 Global Moderator

    "LLMNR in the windows machines"

    hehehehe - you know windows machines pump out way more noise then just the llmnr crap…  The amount of noise coming off a windows machine is quite spectacular...

    So if your going to spend time cutting down its noise that is just the first place to start...

  • Banned

    Assuming that you have AD in place (you most certainly should with ~300 devices), you should disable the service via GPO.

  • LAYER 8 Global Moderator

    disable llmnr in gpo yup..

    Computer Configuration -> Administrative Templates -> Network -> DNS Client
    “Turn Off Multicast Name Resolution” and set it to “Enabled”

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