Use DNS to distribute page requests evenly among multiple servers

The term is called 'round-robin' DNS and basically allows you to assign more than 1 IP address to a given hostname.  If setup properly, round-robin DNS will actually loop through the list of IP addresses when resolving a host name.

Let's say you're running a site on 3 different server with IP address: 192.168.28.1, 192.168.28.2, and 192.168.28.3.  You can configure round-robin DNS to cycle through the above three IPs with each request.  The first request will route to 192.168.28.1, the second to 192.168.28.2, the third to 192.168.28.3, and the fourth would return to the top of the list 192.168.28.1.

If you run your own DNS server, your zone file would look similar the following:

If you are using a DNS service provider, chances are that they probably do not offer round-robin DNS.  A good provider that does offer round-robin DNS can be found on the Free DNS page.