To reduce false positive alerts, NerdTools uses a confirmation process before declaring your site is down. You can customize this behavior using the fault tolerance setting.
The confirmation process
- Initial failure detected — A check returns an error or timeout.
- Local confirmation — The system retries the check from the same location.
- Remote confirmation — If local checks still fail, the system checks from additional geographic locations.
- Downtime confirmed — After confirmation, the site is marked as down and an alert is sent.
Fault tolerance presets
Choose a preset that matches your needs:
- Low — Minimal confirmation with a single retry. Alerts are sent quickly, but you may receive more false positives from transient network issues.
- Medium (default) — Balanced confirmation with multiple retries. A good default for most sites that provides reasonable alert speed while filtering out brief glitches.
- High — Extended confirmation with more retries. Reduces false positives but delays notification of real outages. Best for sites with known intermittent issues.
Balancing speed vs accuracy
Lower fault tolerance means faster alerts but more false positives. Higher fault tolerance means fewer false alerts but slower notification of real outages. Choose the preset that best fits your tolerance for each.