Administrative distance is something that Cisco created to keep a track of routes when multiple routing protocols are in use on a router. It is the believability/reliability of the routes in a routing table. When the same route is received on a router from differing routing protocols, there needs to be a decider on which protocol is to be preferred. It is a list that goes from the most preferred/accurate to the least.
You are able to manipulate the AD of processes on the router. If you do manipulate these values then you need to do this for all of the routers in the network or you really need to know exactly what you are doing.
|ROUTE SOURCE||ADMINISTRATIVE DISTANCE|
|EIGRP Summary Route||5|