Hello, I have been directed to this list by IANA when I asked the following question: I am researching ways of device/machine discovery on the network. This is similar to the Discovery phase of UPnP devices, which uses the SSDP protocol. I have researched far enough to know that my best bet for UDP multicast address group is the Site-Local Scope address range of 239.255.000.000-239.255.255.255 SSDP and UPnP protocols use the address 239.255.255.250 My question is this: How do I pick a group address within this range and not have a chance of colliding with some other application on the network already using the group address I just picked? Do I just randomly pick an address in that range and hope for the best? I am running on Windows and cannot assume that there is a MADCAP server available. Thanks in advance! Dave Raskin Rimage Corporation