Real interesting, it turns out. For example, load balancing isn't restricted to a server farm at a single location. Load balancers can also be turned around, permitting Web requests originating from internal network users to be effectively distributed across firewalls and proxy servers. They can also ensure preferential treatment for a site's best customers. However, before we get into the interesting directions that load balancing is taking, let's quickly review the technology's recent past.
Load balancers exist because networks are faster than the systems they connect.
The next step was to not only check to see if the servers were still alive but also to determine how well they were performing. That way, if a server became overburdened, incoming requests could be sent to other machines to ensure that the overall load was well-balanced across all available resources. As Web services became more sophisticated, however, simply monitoring a single tier of Web servers was no longer sufficient. New services such as online retailing began to use multiple tiers of servers for content, databases, and transaction processing engines. The fact that these new e-business services now involved real money also made it more important to ensure the best possible performance for customers.