One of the vital features of ArcGIS for Server is load balancing. How a GIS server can take over in case others are busy or highly loaded is certainly a very important aspect of maintaining good response time. When a request is made to consume a GIS service, the Web server (whether dedicated or built in) keeps logs in the Server site. These include which GIS server is free and which one is not. The decision regarding which GIS server should get this request next is made accordingly. The server then executes the request efficiently using the optimization tools we discussed in Chapter 5, Optimizing GIS Services. The load balancing module is a closed box, which means you get to enjoy the experience of Server balancing the requests between your GIS servers but cannot peek under the hood and configure it. It would be really useful if Esri were to expose this part for us to play with; it did, however, enable us to tap into something really interesting—clustering...