What does administrative distance rank?

Administrative distance is a metric used by routers to determine the trustworthiness of a routing source or path. It ranks routing sources or routes received from different routing protocols according to their reliability and preference. Essentially, administrative distance is a value used by a router to choose the best path when there are multiple routes to the same destination from different routing sources. The lower the administrative distance value, the more trustworthy the route. Different routing protocols have default administrative distances. For example, routes learned from directly connected networks have an administrative distance of 0, which is the most trusted. In contrast, routes learned from less reliable sources, such as external Border Gateway Protocol (eBGP) routes, have higher administrative distances.