Your monitors are checked from Paris. When a check fails, a probe in Amsterdam checks the same thing again before we alert you. The alert then tells you which step failed, so you know where to look first.
Why a second location
One failed check from one place can be a blip in the network between that place and your server. Your site may be fine for everyone else. A second check from another city tells the two apart, so an alert from us means your site failed from two places. If the Amsterdam probe can't be reached, Paris decides on its own, so a problem with the probe never hides an outage.
What happens, step by step
- Paris checks on schedule. Every minute on Pro and Business, every 5 minutes on the free personal plan.
- A check fails. Paris checks again about 15 seconds later, and Amsterdam runs the same check at the same time.
- Amsterdam sees the failure too. The outage is confirmed: we alert you, an incident opens in the app, and your status page shows the service as unavailable.
- Your site answers again. The incident is resolved automatically, with the time it came back.
Where it failed
Loading a web page takes four steps. The alert names the first one that failed.
| Step | What failed | Where to look first |
|---|---|---|
| DNS | Your domain name didn't resolve to an address | Your DNS host or domain registrar. Has a record changed, or has the domain expired? |
| Connect | The server didn't accept a connection | Your hosting company or server. Is it running, or is a firewall in the way? |
| TLS | The secure connection couldn't be set up, often a certificate problem | Whoever renews your certificate. SSL Monitor warns you before a certificate expires |
| HTTP | The server answered with an error, like 503 | Your website or the app behind it, and the person who runs it |
An example
A fictional webshop, checked every minute on Pro:
- 10:10Paris: HTTP 503
- 10:10Confirmed from Amsterdam: HTTP 503
- 10:10Alert sent by e-mail and to Slack. It says: failed at HTTP response
- 10:10Status page: Webshop is unavailable
- 10:14Webshop answers again. Resolved automatically
What Amsterdam keeps
Nothing. The Amsterdam probe runs the confirming check and passes the result back. It stores no data. Everything Uptime Monitor keeps, like check results, incidents and your status pages' history, is stored in Paris, with no US sub-processors.
Every plan gets the confirmation from Amsterdam, including the free plan for personal sites.