How to identify unique user?

Question

Question

How can you determine if a user is unique or not?

I understand there are many ways to do this using cookies, but what about methods that don\'t us

Answer 1

I'm guessing that Urban Dictionary (and other voting sites, such as a variety of image boards) use IP addresses to track visitors. Not 100% fool-proof, but probably pretty good for most of the time.

Note that with many of these sites, you can vote again, usually once per 24 hours (or however long they log IP addresses for).

Some things that will break this scheme: People who know how to spoof IP addersses, NAT routers, proxies (possibly). Another thing: many home ISPs these days use dynamic IP addresses, so the IP address you have right now might be different in a few hours. If you want to force a new IP address, it's usually enough to unplug your high-speed modem for a few minutes then plug it back in. Some routers also have a feature to demand a new IP from the ISP.