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Administrative Distance

Written on by admin on. Posted in Cheat Sheets

Administrative Distance is reliability assigned by routers to a routing protocol. When a router learns the same route from different routing protocols, then the route learned from protocol with the lowest Administrative Distance (AD) is preferred over the others. For example the router learns a route to via OSPF and via RIP, then the one learned via OSPF is the preferred one.

In table bellow you have default Administrative Distances for routing protocols:

Source Protocol Administrative Distance
Direclty Connected 0
Static Route 1
EIGRP summary route 5
External BGP (Border Gateway Protocol) 20
Internal EIGRP (Enhanced Interior Gateway Routing Protocol) 90
IGRP (Interior Gateway Routing Protocol) 100
OSPF (Open Shortest Path First) 110
IS-IS (Intermediate System to Intermediate System) 115
RIP (Routing Information Protocol) 120
ODR (On Demand Routing) 160
External EIGRP 170
Internal BGP 200
Unknown* 255
* If the route has an Administrative Distance of 255, the route is not used by the router and it is not installed in routing table.

Comments (3)

  • Raja


    IGRP: Interrior Gateway Routing Protocol. Its mentioned as Internet Gateway Routing Protocol.


    • admin


      Oops, sorry for mistake! Thanks for mentioning it!


  • Abir


    GooD WorK


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