First we look at the route that will be taken to get to our destination. To find out what route will be taken, type
This will return a list of hops that your data packet must take to reach its destination. While the output from this tool is can be a fascinating look at the winding path of your data, we are really only interested in the first line, which in my case looks like this:
1 10.0.1.1 (10.0.1.1) 0.454 ms 0.437 ms 0.428 ms
This tells me that the first hop is from my laptop to 10.0.1.1. Now I can the route tool to determine which internet connection is going to this location. I type
and the output tells me
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
default 10.0.1.1 0.0.0.0 UG 100 0 0 eth0
default 192.168.0.88 0.0.0.0 UG 600 0 0 wlan0
10.0.1.0 * 255.255.255.0 U 100 0 0 eth0
link-local * 255.255.0.0 U 1000 0 0 virbr0
192.168.0.0 * 255.255.255.0 U 600 0 0 wlan0
192.168.122.0 * 255.255.255.0 U 0 0 0 virbr0
Again, I am only interested in the first few rows. You can see that I have a default route going to the gateway 10.0.1.1, and the Use Iface column tells me that this uses the eth0 interface, which is my wired connection. (The wlan0 is my wifi, and the virbr0 is a virtual bridge, in case anyone is curious).
So connections to the someaddress.com website (which is a stand-in for anything real I would use there) run through the 10.0.1.1 gateway over the wired eth0 connection, and I don't need to worry about disconnecting my wifi to ensure that I get high speed for my download.