There are a few key characteristics you likely want to focus on as you design your environment:
Each of these characteristics is best approached separately, as often there is an exchange or balance to be made. This is especially true for performance and security, as these two characteristics often seem to conflict. It is especially challenging to find an acceptable balance between them.
One of the keys to building a reliable environment is to expect everything to fail. This pessimistic approach is an essential characteristic of anyone responsible for the creation of the Web application environment.
There are many aspects of your environment that can fail. Servers can fail, network ...