I went to a site today DigNuke.com and when I attempted to register on their site, there is a field that asks "What is 2 + 2? The tooltip gives the answer of 4, but I am wondering a few things:
1. Does this work to prevent spam bots from creating accounts?
if so,
2. How do you set up the field to work?

Upon a guess, I would need to set the answer in validation using regex. I emailed them asking for how they did it, but no reply as of now. I have a site that I have to remove at least 4 bot accounts daily. Since I did a custom registration page that number has dropped, but still, that idea looks intriguing.

Can anyone offer guidance?

I got a reply from DigNuke. I think this works for stopping spam bots. At least I haven't gotten any new fake registrations in the past few hours.

Hi,
Just make a new profile property:
Data Type: Integer
Validation Expression: 6 (or whatever your question answer will be)
Required: Yes
Visible: Yes
Thanks

For some other pointers on stopping spam registrations, go to the bottom of this page from our friends at DNNHero: http://www.dnnhero.com/blog/the-10-...f-dnn-2014