Mechanisms for blocking repeat voting
These are the main mechanisms we offer to block repeat voting:
1) Blocking repeat voting using the browser - this is not very strong, as users can just delete the browser "memory" to circumvent this mechanism.
2) Blocking repeat voting using IP addresses - this is much stronger and more than enough for most of the cases, however, a more sophisticated hacker can overcome this by writing a bot that switches IP's automatically - not easy, but possible.
3) Blocking repeat voting using social profiles - in this case, you can only vote using a social profile (Facebook, Google, Twitter).
In addition, from the report dashboard, you can export all the vote submissions to verify there aren't any cheat patterns (e.g. irregular submission times, bursts of votes to a specific side, etc).
To add IP vote blocking
1) Edit your poll
2) In the Block repeat voting drop-down, select Block based on browser & IP
To require a social profile to vote
In the poll creation form, enable the Require a social profile to vote checkbox. Note that if your poll was already created you won't be able to enable this setting. In addition, some browsers (e.g. ios) may request users to approve the cookies put for the social profile.
In votes of high-profile in which voters have the motivation to cheat, we recommend not showing users the results before the voting ends. When users see the results, they are more prone to try and "hack" the poll.