This grouping includes all other combinations that we haven't covered yet, but it covers the class of largest deployments that use a tool, HAProxy, which we will cover in some detail later. What it basically does is tie a specific port on the host (that is, <host>:10101 ) to a load-balanced target somewhere else in the cluster.

From the client perspective, they are connecting to a single and stable location and the HAProxy then tunnels it seamlessly to the right target.

This setup supports both pull and push refreshing of methods and is very resilient, but we will take a deep dive into this type of setup in later chapters.