How does dzone.com maintain state of the div?

Question

When you scroll down to the bottom of http://www.dzone.com/links/ it automatically loads more links. However, when you navigate away, then hit the back button, the contents of the modified div stay there. How do they get the browser to go back to a dynamically generated div?

Answer 1

It does not maintain state, when you click back it is just pulling in the page from the history. If you refresh it goes back to the original state.

Answer 2

Figured it out. It's the bfcache. IE reloads the page on the back button, whereas FF saves state.