An application I a built (on Java) requires that I open a multicast socket on 224.0.0.1 so as to send UDP packets. I ran my application on an older Windows XP PC and it works fine. But there seems to be no issues for addresses above 224.0.0.1 (Ex. 224.0.0.2). Additionally, I ran a tracert 224.0.0.1 command on CMD prompt and it gives a Transmit error: code 1232. The same command works fine on the XP pc. Thanks.

Hi Milos, I got the same problem. 224.0.0.1 work fine in winXP but not in Win7. (Both in java and winsock) After a little try. I found 224.0.0.251 can work both in WinXP and Win7. But 224.0.0.251 can only work in LAN Interface, for WIFI interface can't work correctly. I still try to find out the problem. Hope this can help you. Best Regards, Kenny Chang

224.0.0.1 is reserved. This is the Group all multicast hosts have to listen to. It's better not to use that reserved IP. You should use 239.0.0.0/8 IP network instead. You should also keep in mind IP <-> MAC Address mapping in order to avoid MAC Address overlapping, because different multicast IPs can have the same MAC Address.