A domain name is the address people type to reach your site. It is not the site itself, and it is not the hosting.
THE THREE SEPARATE THINGS
- The domain: the name, leased from a registry through a registrar, usually annually.
- The hosting: the server holding your files and email.
- DNS: the system connecting the two, telling the internet which server answers for your name.
You can have any one without the others. A domain with no hosting resolves to nothing. Hosting with no domain is reachable only by IP or temporary URL.
WHAT HAPPENS WHEN SOMEONE VISITS
- The browser asks a resolver for the address behind your domain.
- The resolver asks the registry which nameservers are authoritative.
- It asks those nameservers for the A record.
- It receives an IP address and connects to that server.
- The server returns your site.
WHY THIS MATTERS IN PRACTICE
When a site is unreachable, the fault lies in one of those steps. A domain that has expired fails at step 2. Wrong nameservers fail at step 3. A missing A record fails at step 4. A broken website fails at step 5.
Knowing which step failed is most of the diagnosis.
