Which statements are true about EIGRP successor routes? (Choose two.)

A.
A successor route is used by EIGRP to forward traffic to a destination.

B.
Successor routes are saved in the topology table to be used if the primary route fails.

C.
Successor routes are flagged as “active” in the routing table.

D.
A successor route may be backed up by a feasible successor route.

E.
Successor routes are stored in the neighbor table following the discovery process.

Explanation:
The DUAL finite state machine embodies the decision process for all route computations.
It tracks all routes advertised by all neighbors. The distance information, known as a metric, is
used by DUAL to select efficient loop free paths.
DUAL selects routes to be inserted into a routing table based on feasible successors. A successor
is a neighboring router used for packet forwarding that has a least cost path to a destination that is
guaranteed not to be part of a routing loop. When there are no feasible successors but there are
neighbors advertising the destination, a recomputation must occur. This is the process where a
new successor is determined. The amount of time it takes to recompute the route affects the
convergence time.
Even though the recomputation is not processor-intensive, it is advantageous to avoid
recomputation if it is not necessary. When a topology change occurs, DUAL will test for feasible

successors. If there are feasible successors, it will use any it finds in order to avoid any
unnecessary recomputation. Feasible successors are defined in more detail later in this document.
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.