Checked from four regions, before we wake you up

Monitoring from multiple regions eliminates false positives. A network blip or routing issue in one data center will not trigger an alert, because the other regions must confirm the failure first.

Sentinel checks every site from four global regions: Ashburn (US East), Portland (US West), Nuremberg (Europe), and Singapore (Asia Pacific). Every check runs from all four at once, which is the number that matters: most monitoring services check from one location at a time, however many are on the map.

A site is only marked as down once multiple regions agree on the failure. This consensus requirement means a transient issue in a single region will not wake your on-call team in the middle of the night.

SentinelBot is a verified bot in Cloudflare's Radar directory, so checks from all four regions are recognized as legitimate monitoring traffic on Cloudflare-protected sites instead of being challenged. The user agent is documented and our monitoring IPs are published for allowlisting on other firewalls.

You can see it. Because checks run from four regions at once, the monitor view shows each region's latest result side by side, so a site that's down in Europe but up in North America looks exactly like that. Alerts are reserved for outages the regions confirm together; a blip visible from only one region won't page you. If a specific region matters enough to alert on, such as the market your customers are in, add a second monitor scoped to just that region and it will alert on that region alone.

The check interval depends on your plan, and the fastest plans check as often as every 30 seconds. Whatever interval you're on, all four regions check in parallel: more frequent checks mean faster detection and verification of real outages.

Once an outage is verified across regions, Sentinel sends alerts by email, SMS, Slack, Discord, or webhook and opens an incident with an automatic timeline of which regions were affected.