What is Administrative Distance

Administrative Distance (AD) is a value that routers use in order to select the best path when there are two or more different routes to the same destination from two different routing protocols. Administrative Distance counts the reliability of a routing protocol. Administrative Distance (AD) is a numeric value which can range from 0 to 255. A smaller Administrative Distance (AD) is more trusted by a router, therefore the best Administrative Distance (AD) being 0 and the worst, 255.

Administrative Distance (AD) Route Type
0 Connected interface
0 or 1 Static Route
90 Internal EIGRP Route (within the same Autonomous System (AS))
100 IGRP Route
110 OSPF Route
115 IS-IS
120 RIP Route
255 Unknown Route
Related Tutorials
• Types of Routes - Static Routes and Dynamic Routes
• What is the difference between Routing Protocols and Routed Protocols
• What is Autonomous System and Autonomous System Number
• Introduction to Static Routes and Default Routes
• How to configure Static Routes and Default Routes
• What is Dynamic Routing and different types of Dynamic Routing
• What is Routing Metric Value