With classless routing, a routing table lookup always returns the longest match. This actually means any supernet that contains our destination address. If there is no destination that matches our destination IP, the default route could be used. The default route is a usually defined as 0.0.0.0/0 or 0.0.0.0 0.0.0.0 and is the lowest possible entry in the routing table that will match any route.
Classless routing is the default behavior of the routing table, but if it was changed, you can use it again, with: