Haha!
Amazon will be nowhere near that simple. Usually for this kind of large company, they have different solutions in different datacenters all over the world. Probably load-balanced globally with something like F5's 3-DNS (see http://www.f5.com/f5products/products/bigip/gtm/ ).
Each solution will also be locally load balanced transparently to the user between lots of webservers, and on from there it'll get more complicated with probably caches, application servers and databases at the backend.
Where you get load balanced will depend on where your request comes from, where you're going to and probably lots of performance metrics, too.
So, it takes rather a lot of effort and coordination to take someone like Amazon down. The possible upside on the minds of the bad guys is that while nobody can get to a retailer that exclusively operates on the web they're losing a lot of money and might possibly pay the bad guy to stop attacking. This is usually a bad idea though, as has been mentioned.
Fortunately, we have ways of mitigating organised DDoS style attacks these days. Arbor Peakflow being one - http://www.arbornetworks.com/