HTTP Status Code
An HTTP status code is a three-digit number a server returns to indicate the outcome of a request, such as 200 (OK), 404 (Not Found), or 500 (Server Error).
Status codes group into families: 2xx success, 3xx redirects, 4xx client errors, and 5xx server errors. Monitoring watches for unexpected codes, a 500 where a 200 belongs, or a redirect that breaks, which often signal an outage even when the server still answers.
Checking the status code (not just whether a connection opened) is what separates real uptime monitoring from a simple ping.
What does that status code really mean?
From 200 to 500: look up any HTTP status code and understand whether your server reports success, redirect or error. Free, in seconds.
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