Differences between static routes, default routes, and default gateways
Static route: The routing table is manually configured by the network administrator. The routing table can be used when the network is small.
Default route: When the network is large, it is not suitable to use static routes. Using the default route reduces the workload of the administrator. If the matching fails in the routing table, the routes are forwarded through the default route.
Default gateway: If you want to communicate with different network segments, you must configure the default gateway.
For example, if A needs to send a message to B, it checks whether B is in the same network segment as itself. If B is in the same network segment as B, A directly sends the message. If no, the gateway sends a request to the gateway for forwarding.