A ServiceCIDR is a non-namespaced Kubernetes resource that defines one or more IP ranges for virtual IP addresses assigned to ClusterIP Services. The API server manages the configured Service CIDR, while kube-proxy forwards traffic from Service IPs to backend Pods. Service IPs remain inside the cluster and support service discovery and routing. section 6.2.1 section 6.1
Use these operational distinctions when working with ServiceCIDR:
- Separate the Service CIDR from the Nodes CIDR and Pod CIDR; all cluster IP ranges must be unique. section 6.1
- Allow multiple ranges for IPv4, IPv6, or later address-space expansion; the API chooses a free address from the listed ranges. section 6.2.1
- Delete Services before deleting a ServiceCIDR, because its finalizer blocks deletion while a Service uses an address in that range. section 6.2.1
Reconfigure and verify a Service CIDR
On a fresh Kubernetes v1.34-or-later kind cluster, edit /etc/kubernetes/manifests/kube-apiserver.yaml and change --service-cluster-ip-range from 10.96.0.0/16 to 100.96.0.0/16. After recreating the built-in Services and ServiceCIDR resource, verify the result with kubectl get servicecidr and kubectl get svc -A; expected addresses include 100.96.0.1 for kubernetes and 100.96.0.10 for kube-dns. Update kubelet DNS configuration, then confirm a test Pod uses nameserver 100.96.0.10 and resolves a hostname with nslookup. section 6.1
