Yorgos:
Thanks for the response. But we do not want to receive an answer with ttl = 0 as the application uses the ttl value to start its own refresh timer. For now I have made the timer value tt1+1 if ttl !=0 and ttl=prev ttl otherwise, so applications goes to unbound 1 sec after expiry.
Ideally we want unbound not to send response with ttl=0, instead do the new fetch and return the answer to new fetch without 1 sec delay. After all the application re-queried unbound only after ttl secs expired. The reason is there is certain certification that requires compliance of ttl value for re-queries.
In essence we do not want unbound to maintain cache at all, as the higher application does that, but I could not find a way to configure unbound to not cache. Setting cache-max-ttl to zero has the undesirable side effect of always returning ttl=0 for any query.
Thanks
Sankar