What is NodeLocalDNS?
NodeLocalDNS is an optional feature in Kubernetes that improves DNS performance and reliability by running a small DNS caching server on each node.
Instead of making every DNS request go across the network to the kube-dns or CoreDNS service, the request is handled locally on the node. This reduces DNS lookup latency and avoids overloading the shared cluster DNS service.
Why Use NodeLocalDNS?
- 🧠 Faster DNS resolution — queries are resolved from local cache.
- 📉 Reduced load on kube-dns/CoreDNS — fewer round trips to the central service.
- 🌐 Better reliability — even if CoreDNS has a hiccup, cached results can still resolve.
How NodeLocalDNS Works
Here’s a simplified flow:
- A pod makes a DNS query (e.g. to resolve
my-service.default.svc.cluster.local). - Instead of forwarding it to CoreDNS over the network, the request is sent to a local IP on the node (typically
169.254.20.10). - The NodeLocalDNS agent on the node handles the request — either from its cache or by querying upstream CoreDNS.
This way, DNS traffic stays mostly local to the node.
YAML Example: Enabling NodeLocalDNS
You can enable NodeLocalDNS in your cluster with the following configuration (example for kubeadm):
kubectl apply -f https://k8s.io/examples/admin/nodelocaldns/nodelocaldns.yaml
Check that the nodelocaldns pods are running on each node:
kubectl get pods -n kube-system -l k8s-app=nodelocaldns
Where It Helps Most
- Clusters with high pod churn (pods frequently created/destroyed).
- Workloads doing many DNS lookups.
- Environments with CoreDNS performance issues.
Summary
NodeLocalDNS is a small, local DNS caching layer that reduces pressure on your cluster DNS and speeds up lookups. It’s easy to set up and a great tool for production-grade clusters.
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