Identifying vs. tracking respondents
Identifying repeat responses from a computer
If you choose to use IP addresses, Vista looks at the IP address of the computer that is requesting the survey. If Vista has already received a response from a computer with that IP address, Vista knows that the computer has been used to take this survey previously.
For more information, see Using cookies to identify respondents, Restricting access with an IP address.
Vista email invitations are specifically designed for tracking respondents because they contain the list of names and email addresses that you created for your Vista email invitation. For more information, see Using Invitation Details. Emailing a survey link using your own email program does not take advantage of Vista's automated tracking and resending features.
URL parameters can be used to track respondents, but you will need to send a unique survey link to each recipient with a parameter such as &name=JohnSmith. To create these unique email addresses you will need to use a 3rd party mail merge program. For more information, see Using URL Parameters in a Survey.
Password questions can be used to track respondents, but you will need to have a separate database or spreadsheet associating names and passwords. For more information, see Password Question.