Default Administrative Distance of OSPF

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The default administrative distance (AD) of OSPF is 110.

Administrative distance is a metric used by routers to determine the trustworthiness of routing information received from different sources. It is used to choose the best path when multiple routing protocols are running on the same router, or when multiple routes to the same destination exist in the routing table.

OSPF is a link-state routing protocol that uses a hierarchical network design with multiple areas. The administrative distance of OSPF is used to compare routes learned from different sources. If OSPF learns about a route from multiple sources, it will choose the route with the lowest administrative distance.

By default, the administrative distance of OSPF is 110. This means that OSPF routes are preferred over RIP (120), EIGRP (90), and other routing protocols with higher administrative distances. However, routes learned from static routes or directly connected interfaces have a lower administrative distance than OSPF (0), and are therefore preferred over OSPF routes.

It's important to note that the default administrative distance of OSPF can be changed using the distance ospf command in Cisco IOS. This can be useful in certain situations, such as when you want to make routes learned from another protocol more preferred than OSPF routes.

Overall, the default administrative distance of OSPF is 110, and it's used to determine the trustworthiness of routing information received from different sources.