Which statement about Administrative Distance and multi-protocol routing is true?

• A. Administrative Distance determines protocol preference; lower values are preferred when multiple protocols offer a route.
• B. Administrative Distance is a measure of the speed of a route.
• C. Administrative Distance only applies to static routes.
• D. Administrative Distance is the same as the route metric.

Answer: (A)

Administrative Distance is the trust level assigned to a route source and is used to decide which route to use when the same destination is learned from more than one routing protocol. When more than one protocol offers a route to the same network, the router picks the path from the source with the lowest Administrative Distance and installs that route in the routing table. This is why in multi-protocol environments you often see one protocol’s route preferred over another’s—the AD value makes the source more or less trustworthy, not because of how fast the route can reach the destination.

Within the same protocol, the protocol’s own metrics determine the best path; if two routes have the same Administrative Distance, the router then compares the internal metrics to choose. It’s helpful to remember that Administrative Distance is separate from route metrics and speed—AD is about trust in the source, not the path’s speed or quality.

So the statement is true because it captures the essential role of Administrative Distance: it determines protocol preference by choosing the route from the source with the lowest AD when multiple protocols offer a route.