GKE NodeLocal DNSCache Atlas
Parent: MongoDB Atlas on GCP · Published reference · snapshot 2026-10-23 · skill mongodb-cohort-e97ebaff6742
↓ Facts as markdownall context files
Source-anchored research for GKE NodeLocal DNSCache Atlas. Run status: COMPLETED.
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Structure and components
- For Atlas failures, test SRV resolution with dig SRV _mongodb._tcp.<cluster-host>, resolve each returned node hostname, then test TCP connectivity from the affected workload. Non-SRV URIs bypass SRV discovery but still contain hostnames requiring DNS. (low confidence) [source]
Problems, failure modes and limitations
- GKE enables NodeLocal DNSCache by default in Autopilot, where it cannot be disabled; Standard enables it by default starting at 1.34.1-gke.3720000. (low confidence) (verified as of 2026-10-22) [source]
- Signicat’s December 2023 GKE report described CoreDNS NodeLocal forwarding to kube-dns over TCP, a hard-coded dnsmasq worker limit, and latency spikes coinciding with open connections above that limit. The author recommended Cloud DNS for that stack. This is a historical operational report, not an Atlas benchmark. (low confidence) [source]
- Signicat’s December 2023 report described a hard-coded 20-child dnsmasq limit in its GKE NodeLocal-to-kube-dns stack. Google’s GKE documentation distinguishes legacy kube-dns through version 1.35 from CoreDNS-based kube-dns in version 1.36 and later, so Signicat’s historical observation is not a universal current GKE limit. (medium confidence) (verified as of 2026-10-22) [source]
Facts and statements
- NodeLocal DNSCache places a DNS cache on each GKE node, reducing central DNS load and lookup latency. It is a Kubernetes DNS optimization, not an Atlas feature. (high confidence) [source]
- A July 25, 2025 community report describes intermittent UnknownHostException and server-selection timeouts from GKE Autopilot to peered Atlas despite successful connections. The report supplies no confirmed NodeLocal DNSCache diagnosis or remedy. (low confidence) [source]
- NodeLocal forwards external queries through the local metadata server, bypassing kube-dns. For its cache, positive records expire at the lesser of their TTL and 30 seconds; NXDOMAIN expires after five seconds. (low confidence) (verified as of 2026-10-22) [source]
- DNS egress policies can break NodeLocal resolution. Inspect the actual resolver path and permit its TCP/UDP DNS traffic; a namespace-only selector failed in Argo CD’s historical GKE incident. (medium confidence) [source]
- Mercari’s June 2025 engineering account reports a tenfold reduction in kube-dns calls and tenfold to hundredfold fewer DNS errors after NodeLocal rollout. These are workload-specific observations, not measured Atlas improvements. (low confidence) (verified as of 2025-06-04) [source]
- For kube-dns upstream timeout logs, Google suggests increasing kube-dns replicas; that workaround does not apply to metadata-server timeouts. Autopilot does not support the documented kube-dns-autoscaler customization. (low confidence) (verified as of 2026-10-22) [source]
Children
- Atlas SRV and node-hostname DNS troubleshooting (frontier)
- GKE DNS egress policies (frontier)
- NodeLocal upstream resolver capacity (frontier)
Frontier under this node: Atlas SRV and node-hostname DNS troubleshooting, GKE DNS egress policies, NodeLocal upstream resolver capacity