named dns

Hi all, I set up named to be my caching dns, and changed my resolv.conf to 127.0.0.1 only but now if i "dig www.google.com" first time it takes 500ms second time 1ms, and if i wait 15min and try again it's 500ms again. Can anyone tell me what's the problem and why it doesnt cache the ip's for longer? Also shouldnt there be files in var/log since in named.conf there are two setting for logging. dump-file "/var/log/named_dump.db"; statistics-file "/var/log/named.stats"; Thanx