1 Static Routing – This is the method by which an administrator manually adds routes to the routing table of a router. This is a method for small networks but it is not scalable for larger networks.
2 Default Routing – This is the method where all routers are configured to send all packets towards a single router. This is a very useful method for small networks or for networks with a single entry and exit point. It is usually used in addition to Static and/or Dynamic routing.
3 Dynamic Routing – This is the method where protocols and algorithms are used to automatically propagate routing information. This is the most common method and most complex method of routing. Each routing protocol can have chapters or even whole books written about then. Most of them have one or more RFCs dedicated to them. In fact, the whole of the next chapter is dedicated to dynamic routing.