HTML submit form using a CAPCHA image or a security question which one is more secure?

Question

I've seen developers use various methods to prevent spam on a basic html contact form

Method 1 is where the developer uses a Captcha image and Method 2 where only a Question is asked eg. Are you Human? with a radio button.

Which one is the better one to use and why?

Answer 1

In terms of stopping bots, a captcha image is not as easy to automate as selecting a radio button.

Having said that, there are more and more spam bots that are able to crack captchas. See wikipedia about captcha circumvention.

Answer 2

I'd prefer using captcha image over asking a question. I simple robot will not make it through both methods however, with a question, a customized bot (a bot trained to solve your question or trained to click your radio button) will easily pass through. With complicated Captcha images, a robot cannot be simply trained to know words in the image (it's artificial intelligence) and you're secured from them.

Answer 3

captcha is better that asking a question because captcha letters are random generation and eacha and every person enter same letters in the display box but question is any one can easily did that job.