Hi All, I need info as to what kind of GUID it is, the one return from the call GetNetworkId(). I did this INetwork* pNwk; ... GUID guid; hr = pNwk->GetNetworkId(&guid); It does not seem to be one of the network adapater(or Network Interface Card) GUIDs. Is this network ID or network connection ID, or something else? Actually my real intention is to find out any ID that can be used to trace back to the device in use. For example, if this function call did return one of the NIC GUIDs, then it would be easy to determine from which device is the connection made. MSDN has little info about how we can do this with Network List Manager(NLM) API. That is really frustration! Any comment is welcome. Btw, were there any other way, I also would like to explore. Thanks! Aaron