The administrative distance for internal BGP, or iBGP, routes is 200. Administrative distance is a value used by routers to determine the trustworthiness of routing information when the same destination network is learned from more than one routing source. The lower the administrative distance, the more preferred the route. For example, external BGP commonly has an administrative distance of 20, OSPF has 110, external EIGRP has 170, and internal BGP has 200.
The CompTIA Network+ N10-009 objectives include routing technologies, routing protocol behavior, administrative distance, and path selection. BGP is commonly used for routing between autonomous systems, especially on the internet. Internal BGP is used within the same autonomous system to share BGP-learned routes between routers. Because iBGP routes have a higher administrative distance than many other routing sources, they are considered less preferred when competing with lower-distance routes to the same destination.
Option A, 20, applies to external BGP. Option B, 110, applies to OSPF. Option C, 170, is commonly associated with external EIGRP. Therefore, the correct administrative distance for internal BGP is 200.
