My configuration is very simple, I've two servers A[primary] and B[secondary] geographically distributed with ~120 ms ping distance. Both A and B runs application with ReadPreference.nearest().
I would expect, that reads from A server hits only A mongodb and reads from B hits only B. However it is not working this way. What I observe is that reads from application on B hits B[secondary] only. But reads from application on A hits both A[primary] and B[secondary].
It looks like nearest() does not mean: "read from nearest node, where nearest is where ping time < 15ms" but: "read from nearest SECONDARY node where ping time < 15 ms OR any if no such secondary node".

Is it expected behaviour?