CoreDNS Cache Prefetch Inefficiency
infoPoorly configured prefetch settings fail to proactively refresh popular records before expiry, causing cache misses during high-traffic periods and increasing latency for frequently accessed services.
Monitor coredns_cache_prefetch_count versus coredns_cache_misses_count. If prefetch count is near zero but miss rate is high for known popular services, prefetch is not triggering. Check if frequently accessed records are expiring from cache.
Configure aggressive prefetch for high-QPS clusters: 'prefetch 2 120s 30%' to refresh records requested 2+ times when 30% of TTL remains. For critical services, use 'prefetch 5 60s 20%'. Monitor coredns_cache_prefetch_count to verify prefetching is active. Combine with serve_stale 3600 for upstream failure tolerance.