Which conditions will prevent two EIGRP routers from becoming neighbors? (Choose two.)
- Their K-values do not match.
- Their hold times do not match.
- Their AS numbers do not match.
- Their hello intervals do not match.
EIGRP routers will not become neighbors if the K-values do not match or if the autonomous system (AS) numbers do not match. They also will not become neighbors if EIGRP is not enabled for the proper networks on the local and remote routers. However, routers can become neighbors if their hello intervals and hold times do not match.
The AS number is designed to control the routers with which a router can communicate. If the AS numbers do not match, EIGRP will not exchange routes between the two routers by design and definition.
The K-values are flags that state whether a certain metric component, such as Load, is used. They must match because they regulate how the metric values are calculated. If one router is just using bandwidth and delay to calculate its metric, and another is using bandwidth, delay, and load; they could make contradictory routing decisions that would lead to a routing loop. Because of this possibility, EIGRP requires that the K-values must match before it will allow the routers to exchange routes.
EIGRP does not require that the hello and hold times match. Although this flexibility can be helpful, it can also lead to unforeseen problems if they are accidentally mismatched. The hello interval is the amount of time in seconds to wait before sending another hello packet. The hold time is the amount of time in seconds to wait before declaring a link to be down.
Layer 3 Technologies
Configure and verify EIGRP neighbor relationship and authentication