9.1 Examining the Routing Table  
  9.1.5 Determining the route administrative distance  
A router can discover routes using dynamic routing protocols, or routes can be configured manually on the router by an administrator. After the routes are discovered or configured, the router must choose which routes are the best routes to given networks.

The administrative distance of the route is the key information that the router uses in deciding which is the best path to a particular destination. The administrative distance is a number that measures the trustworthiness of the source of the route information. The lower the administrative distance, the more trustworthy the source.

Different routing protocols have different default administrative distances. If a path has the lowest administrative distance it is installed in the routing table. A route is not installed in the routing table if the administrative distance from another source is lower.

 

Lab Activity

e-Lab Activity: Administrative Distance

In this lab, the students will analyze the effects of using two routing protocols.

 
 

Web Links

What Is Administrative Distance?

http://www.cisco.com/en/US/tech/ tk826/tk365/ technologies_tech_ note09186a0080094195.shtml