ASP.net Ajax Timeout

I am stuck with count down in ajax, I have a small website where I a开发者_StackOverflow中文版sk each user 5 question in 1 min time, after they login using asp.net membership provider. I want when the user time is over he/she must be taken to result page and show the result, I am using asp.net ajax timer, but if the user press F5 his time start again and by pressing F5 he can continue his test.

how can I stop that. also is there a easy way to show countdown using Ajax for 60sec

Regards Arshad

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Anything client side is potentially hackable, so you can't effectively maintain a time limit using only client-side technologies. When they begin a test, keep a DateTime in their Session to indicate that a test has been begun. If the submission comes in after more than the time limit has elapsed based on the server time, then tell them to try again cause they cheated.