Fighting against repetitive clicks
<p>I'm writing an Adsense style adserver now. Want to know which are the best methods to fight against repetitive clicks. Now i'm storing the clickers IP address in an other table, and allow 1 click in every 24hr for an ad. This solution is not the best, and it still can be screwed. How does Google and the others does?</p>

<p>Thanks for the suggestions.</p>
