I have set interest's must-be-fresh flags to true, but cached responses still get returned. See registration process. The only way I was able to force true fresh responses is to include a unique (timestamp) value in the interest prefix.
I would expect that if there is no RIB entry that informs the forwarder where to forward a particular interest to, the NFD would forward the interest on all faces to try to get Data back. This does not seem to be case, or I am doing something wrong. I circumvented this issue by allowing users to re-register with one another, thereby adding the route(s) and informing the forwarder where to forward packets.