Final answer:
In EIGRP, the best entry in the topology table is known as the Successor. It is the primary route used to forward traffic to a destination and is selected based on a metric that considers bandwidth and delay, and potentially other factors like load and reliability. Feasible Successors serve as backup routes and must satisfy certain conditions to prevent routing loops.
Step-by-step explanation:
The best entry in the topology table in EIGRP (Enhanced Interior Gateway Routing Protocol) is referred to as the Successor. A successor is the best path to reach a particular destination network and is the one used to forward traffic.
EIGRP uses a metric calculation based on bandwidth and delay by default, additionally considering load, reliability, and MTU if configured, to determine the best route to each destination.
In addition to the successor, EIGRP may elect a Feasible Successor, which is a backup route that is also loop-free. The Feasible Successor is a valid alternative path that satisfies the feasibility condition, meaning that its reported distance is less than the feasible distance of the current successor route.
The successor is stored in the routing table, while both successors and feasible successors are stored in the EIGRP topology table, providing a quick convergence in case the primary (successor) route fails.