By default, if equal-cost paths exist for the same destination, which action will the router take?

A router will not drop traffic if valid equal-cost paths exist; it will always attempt to forward the traffic.

Making a copy of traffic and sending it to multiple destinations is a characteristic of multicast routing, not standard unicast routing with equal-cost paths.

While load-balancing traffic (ECMP) is a common and often default *enabled* behavior in modern routers, if the question implies a simpler default or a system without explicit ECMP configuration, 'randomly select one' might refer to the path selection mechanism that doesn't necessarily distribute traffic across *all* available paths for *all* flows.

In the absence of explicit equal-cost multi-path (ECMP) configuration, or depending on the router's default hash algorithm and implementation, a router might, by default, select one of the available equal-cost paths to forward traffic. This selection could be based on internal tie-breaking rules, the first path learned, or a hashing mechanism that effectively 'randomly' picks one path for a given flow without guaranteeing distribution across all paths.