Administrative Distance (abbreviation for AD) is a value that routers/Layer 3 switches use in order to select the best path when there are more than 1 routes to the same destination from two different routing protocols.Administrative Distance (AD) is a numeric value which can range from 0 to 255 and is referred as standard for route preference across vendors.
Below table gives the default Administrative Distance for all the Routing protocols –
ROUTE TYPE | ADMINISTRATIVEDISTANCE | ROUTING TABLEENTRY |
| Connected | 0 | C |
| Static Route out an interface | 0 | S |
| Static Route to Next-Hop IP | 1 | S |
| EIGRP Summary route | 5 | D |
| External BGP | 20 | B |
| Internal EIGRP | 90 | D |
| IGRP | 100 | I |
| OSPF | 110 | O |
| IS-IS | 115 | i |
| RIP v1 & v2 | 120 | R |
| Exterior Gateway Protocol (EGP) | 140 | E |
| ODR | 160 | O |
| External EIGRP | 170 | D EX |
| Internal BGP | 200 | B |
| Unknown | 255 |
Watch the below given video for better understanding of Administrative distance:
ABOUT THE AUTHOR
I am here to share my knowledge and experience in the field of networking with the goal being – “The more you share, the more you learn.”
I am a biotechnologist by qualification and a Network Enthusiast by interest. I developed interest in networking being in the company of a passionate Network Professional, my husband.
I am a strong believer of the fact that “learning is a constant process of discovering yourself.”
– Rashmi Bhardwaj (Author/Editor)
