> ## Documentation Index > Fetch the complete documentation index at: https://notes.kodekloud.com/llms.txt > Use this file to discover all available pages before exploring further. # Demo Service Types > This guide explains the four primary Kubernetes Service types using a sample NGINX deployment to help expose applications inside and outside the cluster. In this guide, you’ll learn about the four primary Kubernetes Service types—ClusterIP, NodePort, Headless, and ExternalName—using a sample NGINX deployment. Understanding these service types will help you expose applications both inside and outside your cluster. ## Overview of Service Types | Service Type | Scope | Use Case | Example Port | | ------------ | ------------------------ | -------------------------------------- | ------------ | | ClusterIP | Internal cluster traffic | Internal load-balancing | `80` | | NodePort | Node’s IP + port | External access via node IP and port | `30000` | | Headless | Pod IPs directly | Direct per-pod connectivity (no LB) | `80` | | ExternalName | DNS CNAME mapping | Map service to external DNS (no proxy) | N/A | Before diving in, we’ve deployed three NGINX pods with the label `role=nginx` in the `default` namespace: ```bash theme={null} kubectl get pods # OUTPUT # NAME READY STATUS RESTARTS AGE # nginx-deployment-7ff69d756-8qdv8 1/1 Running 0 3m # nginx-deployment-7ff69d756-hccjn 1/1 Running 0 3m # nginx-deployment-7ff69d756-stpmz 1/1 Running 0 3m ``` *** ## 1. ClusterIP (Default) ClusterIP is the Kubernetes default service type. It allocates a virtual IP reachable only within the cluster. ### 1.1 Service Definition ```yaml theme={null} apiVersion: v1 kind: Service metadata: name: clusterip-svc namespace: default spec: type: ClusterIP selector: role: nginx ports: - name: http port: 80 targetPort: 80 ``` ```bash theme={null} kubectl apply -f clusterip-svc.yaml kubectl get svc clusterip-svc # OUTPUT # NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE # clusterip-svc ClusterIP 10.102.157.139 80/TCP 5m ``` ### 1.2 Testing Internal Access Launch a temporary pod to test DNS and HTTP: ```bash theme={null} kubectl run -i --tty --rm debug --image=curlimages/curl --restart=Never -- sh ``` Inside the debug pod: ```bash theme={null} nslookup clusterip-svc.default.svc.cluster.local curl http://clusterip-svc.default.svc.cluster.local # Should return the NGINX welcome page ``` ClusterIP services are only reachable from within the Kubernetes cluster. Use them for internal microservice communication. *** ## 2. NodePort NodePort exposes a Service on each Node’s IP at a static port, allowing external traffic. ### 2.1 Service Definition ```yaml theme={null} apiVersion: v1 kind: Service metadata: name: nodeport-svc namespace: default spec: type: NodePort selector: role: nginx ports: - name: http port: 80 targetPort: 80 nodePort: 30000 ``` ```bash theme={null} kubectl apply -f nodeport-svc.yaml kubectl get svc nodeport-svc # OUTPUT # NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE # nodeport-svc NodePort 10.98.229.84 80:30000/TCP 5m ``` ### 2.2 Access via Node IP 1. Find a node’s IP address: ```bash theme={null} kubectl get node node01 -o jsonpath='{.status.addresses[?(@.type=="InternalIP")].address}' # e.g., 192.168.121.156 ``` 2. From outside the cluster: ```bash theme={null} curl http://192.168.121.156:30000 ``` This should return the NGINX welcome page. Ensure that your cloud provider’s firewall or on-premise network allows traffic to the `nodePort` range (default 30000–32767). ### 2.3 Internal DNS Resolution Within the cluster, you can still resolve the service by DNS: ```bash theme={null} kubectl run -i --tty --rm debug --image=curlimages/curl --restart=Never -- sh # Inside the pod: nslookup nodeport-svc.default.svc.cluster.local curl http://nodeport-svc.default.svc.cluster.local ``` *** ## 3. Headless Service A headless Service omits the cluster IP (`clusterIP: None`) and returns the IPs of individual pods directly. ### 3.1 Service Definition ```yaml theme={null} apiVersion: v1 kind: Service metadata: name: headless-svc namespace: default spec: clusterIP: None selector: role: nginx ports: - name: http port: 80 targetPort: 80 ``` ```bash theme={null} kubectl apply -f headless-svc.yaml kubectl get svc headless-svc # OUTPUT # NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE # headless-svc ClusterIP None 80/TCP 5m ``` ### 3.2 DNS and Direct Pod Access ```bash theme={null} kubectl run -i --tty --rm debug --image=curlimages/curl --restart=Never -- sh ``` Inside the debug pod: ```bash theme={null} nslookup headless-svc.default.svc.cluster.local for ip in $(nslookup headless-svc.default.svc.cluster.local | grep Address | awk '{print $2}'); do curl http://$ip done ``` Headless Services are ideal for stateful applications (e.g., databases) where you need direct pod access for persistent storage or custom load balancing. *** ## 4. ExternalName ExternalName maps a Service to an external DNS name by returning a CNAME record. ### 4.1 Service Definition ```yaml theme={null} apiVersion: v1 kind: Service metadata: name: externalname-svc namespace: default spec: type: ExternalName externalName: httpbin.org ``` ```bash theme={null} kubectl apply -f externalname-svc.yaml kubectl get svc externalname-svc # OUTPUT # NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE # externalname-svc ExternalName 5m ``` ### 4.2 Testing ExternalName ```bash theme={null} kubectl run -i --tty --rm debug --image=curlimages/curl --restart=Never -- sh # Inside the pod: curl http://externalname-svc.default.svc.cluster.local/get # This request is forwarded to httpbin.org/get ``` ExternalName does not proxy traffic through the cluster—it simply performs a DNS CNAME lookup. Use this to reference external APIs or services. *** ## Further Reading & References * [Kubernetes Services](https://kubernetes.io/docs/concepts/services-networking/service/) * [Service Types](https://kubernetes.io/docs/concepts/services-networking/service/#publishing-services-service-types) * [DNS for Services and Pods](https://kubernetes.io/docs/concepts/services-networking/dns-pod-service/)