A level 1 route is a route with a subnet mask equal to or less than the classful mask of the network address. Therefore, a level 1 route can be a:
- Network route - A network route that has a subnet mask equal to that of the classful mask.
- Supernet route - A supernet route is a network address with a mask less than the classful mask, for example, a summary address.
- Default route - A default route is a static route with the address 0.0.0.0/0.
The source of the level 1 route can be a directly connected network, static route, or a dynamic routing protocol.
Figure 1 highlights how level 1 routes are also ultimate routes.
Figure 2 highlights level 1 routes.