Routing Table Ranking

A

The correct answer is A. administrative distance.

The routing table is a database maintained by a router that lists the available network destinations (prefixes) and the preferred paths to those destinations. When multiple routing protocols are used to advertise the same prefix, the router must determine which route to select. The selection process is based on a set of rules called the routing algorithm, which takes into account various factors such as the source of the routing information, the metric of the path, and the administrative distance of the routing protocol.

Administrative distance (AD) is a value assigned to each routing protocol to indicate its trustworthiness or reliability. It is a measure of the preference of a routing protocol over other routing protocols in the router's routing table. The lower the administrative distance value, the more preferred the route is. If there are multiple routes to the same destination with different administrative distances, the router selects the one with the lowest administrative distance as the preferred route.

Here are the default administrative distance values for some common routing protocols:

• Directly connected interface: 0
• Static route: 1
• Enhanced Interior Gateway Routing Protocol (EIGRP): 90
• Open Shortest Path First (OSPF): 110
• Border Gateway Protocol (BGP): 20

In conclusion, administrative distance is the component of the routing table that ranks routing protocols according to their preferences. It is used to select the best route to a destination when there are multiple routes available in the routing table.