jsp get ip address

Question

whats the best way of preventing someone from voting twice? How do i get the users ip address? What if they are on a large network? will everyone on that network show the sa

Answer 1

If users are behind NAT router or proxy server, you will see them with the same IP address. Therefore, it is not the best way of allowing users to vote once.

An alternative would be to use cookies, but again, it is possible to erase the cookie and vote again.