Which protocol is the main routing protocol used in most IP networks today?

The main routing protocol used in most IP networks today is OSPF (Open Shortest Path First). It is a link-state routing protocol that is widely adopted due to its efficiency and scalability. OSPF works effectively in large enterprise networks and service provider environments because it quickly converges and supports a hierarchical structure with areas, which helps in optimizing route updates and reducing overhead.

One of the key advantages of OSPF is its ability to dynamically adapt to changes in the network, allowing it to find the shortest path for data packets by using the Dijkstra algorithm. This makes it suitable for environments where network topology may frequently change, as it can reroute traffic rapidly without significant disruption.

The use of OSPF in various networking scenarios is also bolstered by its support for IPv4 and IPv6, making it versatile for modern internet protocols. Its widespread support across different networking hardware and software further contributes to its status as the dominant routing protocol in most IP networks today.