Checkmk

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Troubleshooting Lab — November 1, 2026

Host: donatello

Author: Chengwei

Investigated a Checkmk service discovery CRITICAL alert on donatello. Verified Linux host accessibility, Checkmk Agent operation, and connectivity from the monitoring server. The alert subsequently changed from CRITICAL to WARNING.

The remaining warning was traced to an unmonitored Docker bridge interface (docker0). The original communication failure's root cause remains unconfirmed. No configuration changes were made.

Full report: Checkmk Monitoring & Troubleshooting Lab Report (PDF)