Alerts & Notifications

    Flapping detection

    How Lemwatch suppresses monitors that flip up/down repeatedly instead of paging you every flip.

    Updated 2026-07-09
    1 min read
    flapping
    accuracy
    alerts

    Quick answer#

    A monitor is "flapping" when its status flips 3+ times in 15 minutes. Lemwatch sends one summary alert instead of paging you per flip.

    What it does#

  1. Tracks status transitions in a 15-minute rolling window
  2. Marks the monitor flapping at 3+ transitions
  3. Sends one "flapping detected" alert, then goes quiet
  4. Sends a "flapping resolved" alert once stable for 15 minutes

    5. Where to find it in Lemwatch#

    Site → Settings → Alert accuracy → Flap detection.

    How to tune it#

  5. Open Alert accuracy for the site.
  6. Adjust Transitions to flap (default 3) — lower = more aggressive.
  7. Adjust Rolling window (default 15 min) — shorter = catches faster flaps.
  8. Optionally route flap alerts to a lower-priority channel.
  9. Save.

    10. FAQ#

    Do I still get the underlying down alert?#

    Yes — the first down alert always fires. Flapping suppression starts on the third transition.

    Does flapping affect uptime %?#

    No. Every transition is recorded in history; only alerting is suppressed.

    Related#

  10. Why am I getting false alerts?
  11. Alert confirmation gates
  12. Hysteresis band
    13. Was this article helpful?

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    Why am I getting false alerts?

    Diagnose flapping monitors, rotating content, and single-region blips that fire alerts you can ignore.

    Alert confirmation gates

    Lemwatch confirms a failure from multiple regions before alerting, so single-region blips stay quiet.

    Hysteresis band explained

    Lemwatch requires response time to fully clear a threshold before recovering, preventing oscillation alerts.

    How does the Alert Rules builder work?

    The Alert Rules builder lets you compose conditions (metric + operator + threshold + duration) and route matching alerts to specific channels.

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