Zend certified PHP/Magento developer

If I ping whateversite.com, what host am I pinging?

I have this lingering doubt regarding DNS, please excuse the basicness of the question.

If I ping www.whateversite.com, I’m pinging the www host in the whateversite.com domain, right?

If I ping whateversite.com, what host am I pinging?, is it a name server or what?
I notice they usually give different IP adddresses when I ping them.

Any clarification much appreciated.