title: Is it a good idea to save user IP for a day to prevent multiple submissions?
body: <p>I am creating a rate/review website similar to ratemyprofessors.com which allows you to submit ratings without logging in. Does anyone know what kind of spam prevention techniques they use in order to prevent a user from submitting multiple ratings for the same professor? I think they associate your IP address with the professor id and store it in the database for a day or two. Thanks in advance!</p>