If R1 learns two routes to the same destination via the same routing protocol and both routes have the same metric, what will be added to the routing table?

When a router, such as R1, learns two routes to the same destination through the same routing protocol with the same metric, both routes can be added to the routing table. This situation is known as equal-cost multi-path (ECMP) routing. ECMP allows a router to maintain multiple paths to the same destination when those paths share the same cost, enabling load balancing.

By adding both routes to the routing table, the router can distribute outbound traffic across these paths, which can improve bandwidth utilization and provide redundancy. This way, if one path fails, traffic can still be routed through the other available path without significant disruption.

In contrast, having only one route added or neither route added would not take advantage of all available paths. Limiting the routing table to just one route or disregarding both would reduce the efficiency of the network and could lead to network congestion or increased latency if relying on a single path. Similarly, favoring a route with a lower address wouldn't apply in this case, as both routes are treated equally with the same metric.