CKAD — Kubernetes DNS
DNS in Kubernetes
Kubernetes runs a DNS server (CoreDNS) that automatically creates DNS records for Services.
DNS Record Format
| Resource | DNS Name |
|---|---|
| Service (same namespace) | <service-name> |
| Service (different namespace) | <service-name>.<namespace> |
| Service (fully qualified) | <service-name>.<namespace>.svc.cluster.local |
| Pod | <pod-ip-dashed>.<namespace>.pod.cluster.local |
Examples
# From a Pod in the 'default' namespace
# Access a Service in the same namespace
curl http://web
# Access a Service in the 'production' namespace
curl http://web.production
# Fully qualified domain name
curl http://web.production.svc.cluster.local
# DNS resolution
kubectl run test --image=busybox:1.36 --rm -it -- nslookup web
# Expected:
# Name: web.default.svc.cluster.local
# Address: 10.96.45.12
Exam tip: When accessing Services across namespaces, use <service>.<namespace> format. You rarely need the full .svc.cluster.local suffix.
