. の有無での挙動の違いについてどこにも書いてないって言ってる人がいるが、
>>331のFAQにちゃんと書いてあるじゃん。

If you are using Squid-2.4 or later then keep in mind that dstdomain acls uses
different syntax for exact host matches and entire domain matches.
www.example.com matches the exact host www.example.com,
while .example.com matches the entire domain example.com (including example.com alone)