Explanation/Reference:
Understanding BGP Path Selection
For each prefix in the routing table, the routing protocol process selects a single best path. After the best path is selected, the route is installed in the routing table. The best path becomes the active route if the same prefix is not learned by a protocol with a lower (more preferred) global preference value, also known as the administrative distance. The algorithm for determining the active route is as follows:
1. Verify that the next hop can be resolved.
2. Choose the path with the lowest preference value (routing protocol process preference).
Routes that are not eligible to be used for forwarding (for example, because they were rejected by routing policy or because a next hop is inaccessible) have a preference of -1 and are never chosen.
Etc.
References: https://www.juniper.net/documentation/en_US/junos12.3/topics/reference/general/routing- ptotocols-address-representation.html