Understanding Administrative Distance Values - JunOS

The routing process in JunOS assigns an administrative distance (or default preference) to each route that the routing table receives. The default value depends on the source of the route. The preference value is a value from 0 through 4294967295 (232 – 1), with a lower value indicating a more preferred route.

Below is chart of AD values of protocols with respect to JunOS.

In order to understand the concept of AD in more details, kindly also read the article Administrative Distance of IP Routing Protocols - Cisco