AD integrated zones. i plan on reading and learning about them later today. Can some1 please give me a brief and easy intro into what exactly is AD integrated zone ? Say we have a DC with 2 primary zones and 2 AD integrated zones, so what exactly does the "AD integration" mean. 

As i said i plan to read more on the subject as i get home, but it would be nice to have a conceptual understanding before i start studying. 