Tim's right, a reverse DNS may get you the DNS binding, but not always.
For example, big sites often have something like a BigIP or ServIron that does load balancing. So there are lots of computers that DNS claims are
www.google.com, but its unlikely that any computer really has that as its name.
Why do you want this? In most production environments, the DNS naming is completely independent of the box, the box's internal names, etc. And of course, NAT makes IP address of questionable value as well