AR521

[chewosaurus]

In EIGRP, two routers will only form a neighbor adjacency if their K-values (metric weights) match. The K-values correspond to the metric calculation formula and must be identical across all peers in the same EIGRP AS. By default, Cisco uses the values "0 1 0 1 0 0" but none of the options are using these k-values. Hence, we choose which fits best.

When we configure metric weights, the first value is TOS which is always 0. Which means only two options remain.
K5 must be 0 unless K4 > 0, otherwise the reliability term can be rejected. Many IOS versions reject such combination.
This leaves us with only one correct combination "metric weights 0 1 1 1 0 0". Although these aren't default values but are the only ones correct.

Makes sense, thanks.