[squid-users] Implication of positive_dns_ttl?

Hi all,
I'm using the default "positive_dns_ttl 6 hours" in my squid.conf. Does this
mean that Squid will overide all DNS ttl and cache every successfull DNS
lookup for at least 6 hours? If that is the case then this doesn't seem to
be happening for me. From Cache Mngr some positive DNS lookups have ttl as
short as 3min and the ttl do go negative after the 3min. Is there a means to
force positive DNS lookup to be cached longer than the ttl provided by the
host domain? Thanks.