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Windows Firewall: Prohibit unicast response to multicast or broadcast requests

Description:

Prevents this computer from receiving unicast responses to its outgoing multicast or broadcast messages.

If you enable this policy setting, and this computer sends multicast or broadcast messages to other computers, Windows Firewall blocks the unicast responses sent by those other computers.

If you disable or do not configure this policy setting, and this computer sends a multicast or broadcast message to other computers, Windows Firewall waits as long as three seconds for unicast responses from the other computers and then blocks all later responses.

Note: This policy setting has no effect if the unicast message is a response to a Dynamic Host Configuration Protocol (DHCP) broadcast message sent by this computer. Windows Firewall always permits those DHCP unicast responses. However, this policy setting can interfere with the NetBIOS messages that detect name conflicts.






Supported on:

At least Windows XP Professional with SP2

GPO PowerShell Regedit CMD

We can use Command Prompt to add or delete the registry key(s):


For Enabled, Add the registry key:

REG add "HKLM\Software\Policies\Microsoft\WindowsFirewall\DomainProfile" /v DisableUnicastResponsesToMulticastBroadcast /t REG_DWORD /d 1 /f


For Disabled, Add the registry key:

REG add "HKLM\Software\Policies\Microsoft\WindowsFirewall\DomainProfile" /v DisableUnicastResponsesToMulticastBroadcast /t REG_DWORD /d 0 /f


For Not Configured, Delete the registry key:

REG DELETE "HKLM\Software\Policies\Microsoft\WindowsFirewall\DomainProfile" /v DisableUnicastResponsesToMulticastBroadcast /f