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How can I configure my DHCP clients to request unicast responses from my DHCP server?
John Savill
September 15, 2002
1 Min Read
A. Unicast is any network communication between a single sender and a single receiver. DHCP server responses typically use multicast communication to broadcast to all DHCP clients within a limited broadcast address (e.g., 255.255.255.255). However, you can configure the registry on Windows NT 4.0 or later DHCP servers to let clients request a unicast response, rather than a multicast response, from the DHCP server by performing the following steps:
Start a registry editor (e.g., regedit.exe).
Navigate to the HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesDHCPServerParameters registry subkey.
Double-click IgnoreBroadcastFlag (or create this value of type DWORD if it doesn't already exist).
Set IgnoreBroadcastFlag to 1 to ignore the DHCP client request flag and always multicast responses or 0 to let the client choose between unicast or multicast, then click OK.
Close the registry editor.
Reboot the server.
Pre-NT 4.0 DHCP versions will ignore this registry setting.
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