Is the failure in the site or in the hosting

The exact boundary between the two

Hosting is the machine, the web service listening on it, the database service, disk space, resource limits and the network path to you. The site is what runs on top: the CMS, its modules, its theme, its configuration files, its data.

The simplest rule is this: if the server returned anything at all, the hosting is working. An error page, a CMS message, a blank page, a half-built page: all of these mean a machine received the request and sent a response. The problem is then in the application in the vast majority of cases. Conversely, no response at all, a message written by the browser itself, or a page generated by the host are signs of an incident upstream of the site.

When the answer is "both"

Some incidents genuinely are mixed, and that is where method matters most. A site consuming too much runs into a hosting limit, but the cause is a badly written query. Failing mail involves both the server configuration and the CMS settings. A PHP version change decided by the host breaks a module that was out of date.

• In those cases, raising the resource makes the symptom vanish without touching the cause, and the problem returns months later.
• Fixing the code without adjusting the limit sometimes leaves too little headroom for peaks.
• The right approach is to measure first, then decide what is a setting and what is a correction.

I work alone and I act on both sides: I read the code as well as the server logs. That removes the back and forth between a developer blaming the hosting and a support desk blaming the site.