There are two ways to update OSPF routing tables:
1. Automatic updates: OSPF routers automatically update their routing tables when there is a change in the network topology. When a change occurs, such as a new link being added or an existing link being removed, the routers exchange link-state advertisements (LSAs) to update each other’s database. As the LSAs are received, the routers use a shortest-path first (SPF) algorithm to recalculate the best routes. The result is a new routing table that reflects the updated topology.
1. Manual updates: OSPF routing tables can also be manually updated by an administrator. This can be done by adding or removing routes in the routing table on each router individually, or by redistributing routes from other routing protocols into OSPF. Manual updates are typically only used when there are specific routing requirements that cannot be fulfilled automatically by OSPF.
