Configuring Multicast Settings

Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2

You can configure Windows Firewall so that Windows Firewall blocks all unicast responses to outgoing multicast or broadcast traffic. When you enable this setting, and your 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 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.

This 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 setting can interfere with the NetBIOS messages that detect name conflicts.

When to perform this task

You should perform this task if your computer sends broadcast or multicast messages and you want Windows Firewall to block all unicast responses.

Task requirements

No special tools are required to perform this task.

Task procedures

To complete this task, perform the following procedure:

Block Unicast Responses to Multicast Traffic

See Also

Concepts

Known Issues for Managing IPsec, Multicast, and ICMP Settings