Cisco Certified Network Associate (CCNA) Practice Exam 2026 - Free CCNA Practice Questions and Study Guide

The correct answer is the visibility of neighbors through the `show eigrp neighbors` command. This command provides a list of all routers that have established EIGRP adjacency with the local router. Proper operation of EIGRP heavily depends on these neighbor relationships, as they are essential for EIGRP to exchange routing information and for the protocol to function effectively. If neighbors are listed, it indicates that the routers can communicate and share routing updates; this is a strong indication that EIGRP is configured and operating correctly.

While stability of routing tables can also reflect EIGRP's performance, it does not directly indicate whether EIGRP is functioning; routing table stability can be influenced by other factors or even by different routing protocols. The frequency of hello packets indicates the maintenance of neighbor relationships but does not directly confirm established connections. Lastly, while having all routes active in the routing table may suggest effective routing, it does not directly correlate to EIGRP's operational state or to its effectiveness in exchanging routing information. Hence, observing the output of the `show eigrp neighbors` command is the most direct and relevant way to assess EIGRP's operational status.