Loading a Questionnaire help?

Hi All,

I have a quick question. I’m thinking of putting a questionnaire on my site via a pop-up window.

Now, the first time a visitor comes to my website they get the pop-up, but if they click/button on a link in the pop-up which says don’t show me again next time they visit the pop-up won’t appear and will continue to not appear.

So my question is what is the best way of doing this? Grabbing the user’s IP address and saving it in a database, and querying that database every time they visit, or would it be better via a cookie, or maybe someone can suggest a different way and point me in the direction of a good tutorial?

Thanks

Dynamic IP addresses change, so I would use cookies.
Cookies can be deleted, but most people don't delete them.

If it's really a serious issue and the questionnaire can only
be filled out once, you would have to go with a user registration thing.