For background, wire a connection and then get a command prompt (on win7:- search, enter CMD and return)
In the new window, enter
route print and enter.
The result is the ROUTING TABLE. Under IPv4 Route Table
are 5 columns; the forth is the Interface (the ip address needed to send traffic out of your system).
Notice there are only two different addresses; 127.0.0.1 (the local loop back, aka localhost) and some other
address that is similar to the address shown under the Gateway column. The Gateway address is pointing to your
router and it is where data must come and go; eg your Interface->the Gateway-->the your ISP.
Usually, the first line in the routing table is the
default route and starts with
One way or the other, all network traffic will exit your system using the
default route.
Now for fun, also make a WiFi connection to your router and repeat the
route print cmd.
There are a few more lines added to the route table but notice that although the WiFi address is
visible (the third unique IP address in the Interface column),
there is NO means for it to access the default route.