suppose i set session time is 30minutes.
and a survey need 60minutes to answer, what's the worst result?

Session time start at 0 each time user click on next page.

so, if user's internet connection broke, and 60minutes later, user come back to continue the survey.
what problem will it cause?

Start the survey at start (except if token)

some answers are already record in mysql.why restart the survey from begining?

iscar wrote: some answers are already record in mysql.why restart the survey from begining?

Because we can not validate is the good user (response ID are in $_SESSION and never elsewhere for security).

Denis

if i use token and multiple answer for one token, when user come back to survey, what will be displayed?