Forward-zone Question

[Thomas Plant via Unbound-users]

Hello Unbound experts,

I'd have a beginners question. If I set a forward-zone as in the 
following example:

forward-zone:
    name: "."
    forward-addr: a.a.a.a
    forward-addr: b.b.b.b
    forward-addr: c.c.c.c

In which order are the request send to the forward targets? Always to 
the first and only in case of failure to the second or a round-robin kind?

Thanks,
Thomas P.