These days, Multi-Tier Applications are the norm. From SharePoint’s front-end/back-end configuration, to LAMP-based websites using multiple servers to handle different functions, a multitude of apps require public and private-facing components to work in tandem.
Placing these apps in entirely public-facing platforms and networks simplifies the process, but at the cost of security vulnerabilities. Locating everything across back-end networks causes headaches for the end-users who try to access the systems over VPN and other private links.
