"This tutorial describes the installation of an ISPConfig 3
multiserver setup with dedicated web, email, database and two DNS
servers all managed trough a single ISPConfig 3 control panel. The
setup described below uses five servers and can be extended easily
to to a higher number of servers by just adding more servers. E.g.
if you want to have two mailservers, do the setup steps from
chapter 2 on both of these servers. If you want to set up more web
servers, then install ISPConfig on all other web servers in expert
mode except of the first one."