Early-generation server load-balancing technology has proven to be an invaluable asset, especially for organizations hosting widely utilized Web applications. By operating as a virtual entry point to such applications, load balancing provides an opportunity to execute a variety of algorithms for splitting the processing load among back-end servers. In addition, periodic polling to establish the status of participating nodes can be used not only to fine-tune the load distribution but also to avoid directing traffic to servers that are actually offline. In other words, server load balancers (SLBs) are a simple yet highly effective means to scale an application environment while simultaneously ensuring its availability.

What the changes and trends expose, in particular, is the need for enterprises to step up from a simple load-balancing solution to a more comprehensive application delivery solution -- a solution that addresses not just scalability and availability of the application environment, but application performance and security as well. Accordingly, this paper is intended to serve as a guide for organizations looking to replace their early-generation SLBs.