What is the Feasible Distance in EIGRP and how does it relate to Advertised Distance?

• A. Feasible Distance is the metric from the neighbor to the destination; Advertised Distance is the total metric from this router.
• B. Feasible Distance equals the Advertised Distance for the same destination.
• C. Feasible Distance is the total metric from the router to the destination; Advertised Distance is the neighbor's metric to the destination.
• D. Feasible Distance is only used in OSPF; Advertised Distance is for RIP.

Answer: (C)

In EIGRP, Feasible Distance is the total metric distance from your router to a destination when using a route via a specific neighbor. Advertised Distance is the metric that the neighbor reports for reaching that destination—the distance from the neighbor to the destination.

FD is found by adding the cost to reach the neighbor to the neighbor’s Advertised Distance. This gives the overall distance from your router to the destination through that neighbor, which you store as the route metric and use to compare paths. The feasibility check uses these values: a route via a neighbor is considered feasible if the neighbor’s Advertised Distance is less than your current Feasible Distance for that destination, helping ensure loop-free paths.

For example, if the cost to reach a neighbor is 10 and the neighbor advertises a distance of 25 to the destination, the Feasible Distance via that neighbor is 35. This is the metric you compare against other routes.