CCNA 3.2.e: Administrative distance


Administrative distance is what is used to select the best path when a router has two different paths to the same destination via two different routing protocols.


Study Notes:

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  • Most routing protocols are not compatible with other protocols.
  • In a network with multiple routing protocols, being able to select the best path between multiple protocols is critical.
  • Administrative distance defines the reliability of a routing protocol.
  • Each routing protocol is prioritized in order of most to least reliable (believable) with the help of an administrative distance value.
  • IPv6 uses the same distances as IPv4.
  • Default Administrative Distances:


Routing Protocol

Administrative Distance
Connected 0
Static 1
BGP (external) 20
IGRP 100
OSPF 110
RIP 120
BGP (internal) 200

See CCNA 3.3.a: Admin Distance for a full list

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