How siteupdown.com checks a website, and what the verdicts mean

We would rather tell you “not sure” than be wrong. This page explains exactly what happens when you press Check, and what each verdict does and does not prove.

The server check

First, our own server looks up the site’s address, connects to it and requests the page, as a browser would. We record the HTTP status code, the response time, the redirects followed on the way, and the details of the SSL certificate. We only contact public web addresses on the standard web ports, and we refuse private or internal addresses, so the checker cannot be used to probe someone’s private network.

The regional probes

Then fifteen probes on the public Globalping network, in different countries, request the same address at nearly the same moment. This shows whether a site is reachable from everywhere, or only from some places.

What the verdicts mean

• Up. The site answered normally. Any response that is not a server error or a block counts, so even a 404 page means the server is alive.
• Down. The server returned a server error (5xx) on two attempts in a row. We always retry once before using this word.
• Timeout. The site did not answer in time. It may be down, overloaded, or just very slow, so we say so instead of declaring it dead.
• Inconclusive. We could not tell. This happens when a site blocks automated requests (a 401, 403, 429 or 451 response), when the name does not resolve, when we cannot connect or verify the secure connection from our server, or when a site redirects in a loop. None of these proves the site is down, so we do not say it is.

Down for everyone, or just you?

If the server check and most probes succeed, the site is up and the problem is likely your own network, DNS, browser or device. If most fail, it is down for everyone. Mixed results usually mean a regional problem. See why a site can be down for some people and not others.

Watchlist alerts

Watched sites are re-checked about every minute. To avoid false alarms, a site is only reported as down after two failed checks in a row, and you get a second email when it recovers, with how long it was down. Inconclusive results never trigger an alert, while a Timeout counts as a failed check.

The limits

Every result is a snapshot of one moment. A short outage between two checks can be missed, and a site behind a strict firewall may look worse than it is for real visitors. Use the result as strong evidence, not as proof.

Related guides

• Why a website can be down for some people and not others
• Uptime percentages explained: what 99.9% really means
• HTTP status codes explained: what 200, 301, 404 and 503 mean

Last updated 2 November 2026. Written by the siteupdown.com team. Spotted a mistake?

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