Where content lives

The name leads to an address, the address to a machine. This page explains what happens there, from the point of view of somebody running a website, not from the point of view of a data centre.

One server, many websites

A web server is the program that accepts requests from the network and returns files or results. It does not serve one website but many: the browser sends along the name it wants, and the server decides which website is meant. That mapping is called a virtual host.

This is why a domain does not automatically work as soon as it points at the right address. The server has to know the name as well. If the domain points at a server that has no mapping for it, you get somebody else’s page or an error.

Every virtual host has a document root, the directory the server delivers from. Everything below it is reachable, everything above is not. Anyone who puts credentials or backups into that directory by accident has published them.

Shared, own, managed

Three ways of operating, differing in who is responsible for what:

With shared hosting many customers run on one system. The provider maintains the operating system, web server and runtime, you supply content. Cheap, little effort, little freedom.

With your own server (physical or virtual) you have full control and full responsibility, including security updates.

With managed hosting of a specific application, WordPress for example, the provider also maintains that application. The difference from shared hosting is not the hardware, it is who installs the updates.

What “cloud” means

The term describes no technical procedure but an operating model: computing power, storage and services are not bought but consumed on demand and provisioned through an interface. Three properties matter: billing by consumption, provisioning in minutes rather than weeks, and operation through an API rather than an order form.

The common distinction is by depth of responsibility. Consume only infrastructure and everything above it stays your job. Consume a platform and you hand over running the runtime. Consume a finished application and you hand over everything except using it.

Size has nothing to do with it: by this classification a single managed mailbox is a finished application, while a rented virtual server is infrastructure.

What this means for a domain

For a website to be reachable, three things have to line up: the domain points at the server’s address via an A or AAAA record, the server knows the name as a virtual host, and a certificate for exactly that name exists. If one is missing the error looks different in each case, and checking in that order saves time.

Your own packages and their mappings are in the dash.