When EIGRP returns a stuck in active message, this means that it has not received a reply from a query. It sends a query when a route is lost and another feasible route does not exist inside the topology table. The SIA is caused by 2 sequential events:
The reported route by the SIA has gone away.
An EIGRP neighbor (or neighbors) have not replied to the query for that route.
When the SIA occurs, the router clears the neighbor that did not reply for the query. When it happens, determine which neighbor has been cleared. We should Keep in mind that this router can be many hops away.
