I would like to let dig always forget a DNS record.I mean if I do dig yahoo.com then I have a record back in with ttl for 1790 seconds.Even if I have no cache service installed, next time i do the same command, the ttl have lowered.Some how, dig do remember the answer. Is it possible to clear that, so I always get a fresh answer back? 
Force dig to forget records
dns;cache;dig
dig doesnt remember queries. But it makes use of name servers listed in /etc/resolv.conf, unless the server to be queried is specified explicitly. Such servers normally accept recursive queries and have caches for their results. So dig can receive records cached by (intermediate) servers.Usedig +trace to override this behaviour, forcing it to query an authoritative server. See dig(1) for more information.