Network programming and how to access a Web site server for all the ip address?

Youku such as network
youku have a large number of users, each user will take up a lot of resources.Therefore, youku deployment of a large number of servers in order to reduce the load on each machine.
Now need to know all youku server address, How should it do?
Take the trouble to give you an idea ~

ping www.youku.com-t know the IP