What does 'Active' mean in the EIGRP topology table?

In the context of the EIGRP (Enhanced Interior Gateway Routing Protocol) topology table, the term 'Active' refers to a state where a router is actively trying to reestablish a route to a destination. Specifically, it means that the router has not heard back from some of its neighbors regarding the status of that route and has therefore entered an active state, attempting to resolve this by querying neighbors to determine the best path to that destination.

When a route is marked as active, the router sends out queries to neighboring routers to gather information about the path to that destination network. The goal is to find alternative routes or confirm the existing routes if some information is suspected to be lost. When the router receives responses to its queries and the necessary information about the state of the path is gathered, the route will shift back to a passive state, meaning that the information has become stable and is now valid for the topology table.

The active state is an essential part of the route reconvergence process in EIGRP, illustrating that the protocol is robust enough to handle the dynamics of network changes. Thus, the definition correctly identifies that a router in an active state has lost information about a network, prompting it to actively query neighbors for the necessary routing information.