Can anyone tell me - if you were to enter a online competition and basically you were allowed 10 votes per person per day but you just deleted the cookie and then voted again - would the people at the other end be able to tell if someone had voted say 500 times from the same computer? And if so how?
Your vote will contain an IP address as Fo3nix says, but that address will contain letters and numbers that are used to identify your account as well as your IP. The whole addresss and account code will be the same each time you vote - so the competiion organisers would know if you voted more than once.
Have a read here, in the window 'The text below...'.
I have just tried the test which heathfield linked to, and found that both my IP address, and the ID supplied by reverse-DNS changed after I dropped my connection and reconnected, so, presumably, there is no way of uniquely identifying me!