@pnunn The default route is simply the way out of the network. It's just like driving somewhere. The first thing you have to do is get out of your driveway. On more complex networks there may be other, more specific routes that might be used first, but eventually you'll need a default route. The only exception is at the top level, between ISPs, carriers, etc., where every possible route must be known and the packet gets dropped if there isn't a route. You could route through an interface, but only on point to point links. On Ethernet, there's always the possibility of more than one other NIC out there, so you can't rely on using just the interface.