At several ocassions it appeared that, even within companies and among system administrators, there can be quite some confusion and questions when it comes to domain names, DNS, Certificates, public and especially private keys and the configuration of a software, like for instance Apache.
Who does what, who provides what, where or how is it used, how does it configure and similar items often seems to be mixed up. Though indeed these topics are often related or even need eachother to function correctly, they are very distinct subjects, items and services.
On the following pages you'll find some explanations and hints on understanding what it is and how it can be set up. Not how it must be setup, because often there can be several ways.