Which type of EIGRP route entry describes a feasible successor?

Which type of EIGRP route entry describes a feasible successor?
A . a backup route, stored in the routing table
B . a primary route, stored in the routing table
C . a backup route, stored in the topology table
D . a primary route, stored in the topology table

View Answer

Answer: C

Explanation:

http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080093f07.shtml

Feasible Successors

A destination entry is moved from the topology table to the routing table when there is a feasible successor. All minimum cost paths to the destination form a set. From this set, the neighbors that have an advertised metric less than the current routing table metric are considered feasible successors.

Feasible successors are viewed by a router as neighbors that are downstream with respect to the destination.

These neighbors and the associated metrics are placed in the forwarding table.

When a neighbor changes the metric it has been advertising or a topology change occurs in the network, the set of feasible successors may have to be re-evaluated.

However, this is not categorized as a route recomputation.

Feasible successor is a route whose Advertised Distance (AD) is less than the Feasible Distance (FD) of the current best path. A feasible successor is a backup route, which is not stored in the routing table but, stored in the topology table.