comparing ip adres with database list

I am unsure what you mean. But what I would do is drop a cookie with a
(semi) unique number and store that number in a database. Unless it is
_very_ important users can't vote more than once. The problem with
logging IP's is that there could be more than one PC behind a single
IP. And this is quite often the case.

If a user comes to your site you simple retrieve the cookie with the
number and see if the number already exists in the DB, if so the
person already voted, if not he did not.

I would combine the two and even store the vote in a session variable for extra security if users have to log in to vote (it all depends on how important the unique votes are). Simply said: internet voting can always be tampered with:

• People can change their IP (most ISPs use DHCP, so resetting the modem gives your user a new IP)

• People can delete cookies

• People can quit their browser, thus resetting the session

The more security you put in place, the more you’re disencouraging your user search for a way to cast additional votes.

Best regards

Peter De Berdt