By default, how is the best IGP path determined when there are multiple equal-cost paths to a destination?

A.
first one learned

B.
most recent one learned

C.
random choice

D.
highest next-hop IP address

Explanation:
Multiple Active Routes

The IGPs compute equal-cost multipath next hops, and IBGP picks up these next hops. When there are multiple, equal-cost next hops associated with a route, the routing protocol process installs only one of the next hops in the forwarding path with each route, randomly selecting which next hop to install. For example, if there are 3equal-cost paths to an exit routing device and 900routes leaving through that routing device, each path ends up with about 300routes pointing at it. This mechanism provides load distribution among the paths while maintaining packet ordering per destination.

BGP multipath does not apply to paths that share the same MED-plus-IGP cost yet differ in IGP cost. Multipath path selection is based on the IGP cost metric, even if two paths have the same MED-plus-IGP cost.