CoreDNS Cache Hit Rate Degradation
warninglatencyUpdated Feb 9, 2026
Low cache hit rates indicate CoreDNS is frequently querying upstream servers, increasing latency and resource consumption. This often manifests as high query response times and elevated CPU usage.
Sources
How to detect:
Monitor cache hit rate by calculating hits/(hits+misses). Alert when hit rate falls below 85% for 5+ minutes, indicating inefficient caching that increases upstream query load and latency.
Recommended action:
Increase cache size and TTL settings in CoreDNS ConfigMap. For high-QPS clusters, configure success cache to 10000-15000 entries with 3600s TTL. Enable prefetching for frequently accessed records. Monitor coredns_cache_size to ensure capacity isn't exceeded.