I don't much about this..i know little that only iam trying to explain..........
one thing is that local addresses u can't access by using internet...whatever Ip address systems are assaigned when they r connected to lan are all local IP addresses. when any system is connected to lan if any request is came from that system to outside first that address whether is there or not in network it will check.....,if it is there means it's just data transfer between lan devices.....if it is not there means it will give to the default gateway system...this default gateway is connected to the remote server through some global ip by using any ISP ...so,it will send request to that..............