Multiple forward-addr: _ order of evaluation?

[Harry Schmalzbauer]

 Bezüglich Ralph Dolmans via Unbound-users's Nachricht vom 09.01.2018
10:53 (localtime):
> Hi Harry,
>
> Unbound selects forward addresses in the same way as it selects
> addresses for normal delegations. That is a random selection over the
> list of addresses with an RTT band of 400 msec.

Thank you very much, Ralph.

Unfortunately I'm not sure how to understand RTT in that context.
Is it "wait 400msec for an answer and take next available on it there
was no answer within that timeout?
Of is it, prepare to use new forwarder from list every 400ms, regardless
if there were succesfull or unsuccessfull queries?

Is there any way to influence the round-robin behaviour for a forward
zone clause (besides getting to source code)?
My intention is to have ai failover forwardern, not a load-baöancing.

For multi-A-records, bind has a static override and I think I remember
that I read something similar for unbound too (I'm new to unbound and
broke my glasses – not much reading for today :-( – so I'm not trying to
verify utilizing the man page ;-)


Thanks,

-harry