Static or Dynamic
The decision primarily depends on the type of network. Static routing is manually deciding the routes the packets should take and therefore is suitable for small networks and where topology does not change very frequently. The advantage of having this is that the routers do not have the overhead of tracing all possible roots, but can simply use the routes loaded into them by a human. However, the disadvantage is that if any link on the static route defined by the administrator fails, the entire transmission fails because the router cannot find by itself other existing routes. Also if the network topology changes the administrator must sit on the router and do the entire configuration necessary.
Dynamic routing is routing where the routers communicate with their neighboring routers, use techniques like graph algorithms and discover the most efficient routes to transmit a packet. They can also pick up an inefficient path by themselves in case a router fails on the efficient path.
Static is used on small networks where efficient paths can be determined manually and where configuration doesn’t change frequently. Dynamic is used for larger and more robust networks which are supposed to be fault tolerant and where failure is very costly. As a trade off, one has to invest more on dynamic routers than on static ones.
