What does a router do if it has no EIGRP feasible successor route to a destination network and the
successor route to that destination network is in active status?

A.
It routes all traffic that is addressed to the destination network to the interface indicated in the
routing table.

B.
It sends a copy of its neighbor table to all adjacent routers.

C.
It sends a multicast query packet to all adjacent neighbors requesting available routing paths to
the destination network.

D.
It broadcasts Hello packets to all routers in the network to re-establish neighbor adjacencies.

Explanation:
Introduction to EIGRP
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.
Route States
A topology table entry for a destination can have one of two states. A route is considered in the
Passive state when a router is not performing a route recomputation. The route is in Active state
when a router is undergoing a route recomputation. If there are always feasible successors, a route
never has to go into Active state and avoids a route recomputation.
When there are no feasible successors, a route goes into Active state and a route recomputation
occurs. A route recomputation commences with a router sending a query packet to all neighbors.
Neighboring routers can either reply if they have feasible successors for the destination or optionally
return a query indicating that they are performing a route recomputation. While in Active state, a
router cannot change the next-hop neighbor it is using to forward packets. Once all replies are
received for a given query, the destination can transition to Passive state and a new successor can be
selected.
When a link to a neighbor that is the only feasible successor goes down, all routes through that
neighbor commence a route recomputation and enter the Active state.