Static routing allows routing tables in specific routers to be set up by the network administrator. Dynamic routing use Routing Protocols that dynamically discover network destinations and how to get to them. Dynamic routing allows routing tables in routers to change if a router on the route goes down or if a new network is added.
In Dynamic Routing, Routing Protocols running in Routers continuously exchange network status updates between each other as broadcast or multicast. With the help of routing updates messages sent by the Routing Protocols, routers can continuously update the routing table when ever a network topolgy change happens.
There are three basic types of routing protocols.
Distance-vector Routing Protocols: Distance-vector Routing Protocols use simple algorithms that calculate a cumulative distance value between routers based on hop count.
Link-state Routing Protocols: Link-state Routing Protocols use sophisticated algorithms that maintain a complex database of internetwork topology.
Example: Open Shortest Path First (OSPF) and Intermediate System to Intermediate System (IS-IS)
Hybrid Routing Protocols: Hybrid Routing Protocols use a combination of distance-vector and link-state methods that tries to incorporate the advantages of both and minimize their disadvantages.