Dns

Understanding ndots in Kubernetes DNS Resolution The ndots option in DNS configuration plays a subtle but important role in how domain names are resolved inside Kubernetes pods. Incorrectly configured ndots can lead to unnecessary DNS queries, delays, or failed resolutions. What is ndots? ndots is a setting in /etc/resolv.conf that determines whether a DNS query is treated as a fully qualified domain name (FQDN) or a partial name requiring search path resolution. ...

CoreDNS is one of those quiet heroes in your Kubernetes cluster. It doesn’t get much attention—until DNS stops working, and suddenly everything breaks. Let’s understand how it works — simply. What Is CoreDNS? CoreDNS is the default DNS server in Kubernetes. It’s what helps your pods resolve names like my-service.default.svc.cluster.local to an actual IP address. It’s not just a DNS server. It’s modular, pluggable, and built for cloud-native environments. Why Is DNS Needed in Kubernetes? In Kubernetes, everything is dynamic: ...

Why Add a Custom DNS Zone? Adding a custom DNS zone in CoreDNS can be useful for: Internal testing (e.g., *.local or *.internal) Service discovery for non-Kubernetes services Custom mappings and overrides Step-by-Step Guide 1. Edit the CoreDNS ConfigMap kubectl -n kube-system edit configmap coredns Add a new zone block like this: apiVersion: v1 kind: ConfigMap metadata: name: coredns namespace: kube-system data: Corefile: | .:53 { errors health kubernetes cluster.local in-addr.arpa ip6.arpa { pods insecure fallthrough in-addr.arpa ip6.arpa } forward . /etc/resolv.conf cache 30 loop reload loadbalance } internal.test:53 { hosts { 10.10.10.10 service1.internal.test 10.10.10.11 service2.internal.test fallthrough } } 2. Restart CoreDNS kubectl -n kube-system rollout restart deployment coredns 3. Test the Zone From any pod: ...

Why Use Custom DNS Zones in NodeLocal DNSCache? NodeLocal DNSCache speeds up DNS resolution in Kubernetes by running a local CoreDNS instance on each node. Adding custom zones allows: Fast resolution of static or internal domains DNS overrides without relying on upstream resolvers Separation of internal and external DNS logic Step-by-Step Guide 1. Get the NodeLocal DNS ConfigMap kubectl -n kube-system get configmap node-local-dns -o yaml > node-local-dns.yaml 2. Add Custom Zones Inside the Corefile section, add your custom zone using the hosts plugin: ...

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: ...