The Arc Challenge Explained

[jgrahamc]

http://www.jgc.org/blog/2008/02/arc-challenge-explained.html

[murrayh]

A nice explanation for someone who has not looked into Arc (me).

[0-9a-zA-Z]{10} is what, 840 quadrillion combinations? Just out of curiosity, what happens if we get a 'fnid' collision?

I expect to be serving a few hundred trillion pages in a couple of years time :-p.

[apgwoz]

The article mentions that the fnid could be stored in a cookie. While this is true it definitely would not be desired, as doing so would make it impossible to browse the site with multiple windows,each on different pages.

[olavk → apgwoz]

And it wouldn't work if there were more than one form or link on a page. Or if the user clicked the back-button.