in reply to Quick and easy way to prevent multiple votes?
Cookies wouldn't work well, as they could be deleted by a
knowledgable user, who could then gain infinite votes. The
way that many sites do it (perlmonks and slashdot, for
instance), is by tracking IP. This has some margin of
error because of things like proxies, and people voting
from more than one IP, but is basically the best all-around
way to do it.
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Seekers of Perl Wisdom