CKAD Services and Networking Practice Question
You create a Service with the following YAML: ``` apiVersion: v1 kind: Service metadata: name: my-service spec: ports: - name: http port: 80 targetPort: 8080 selector: app: my-app ``` What is the default Service type?
⚠ Common exam trap
Many exam-takers assume `NodePort` is the default because it's commonly used in examples, but Kubernetes explicitly defaults to `ClusterIP` when no `type` is set.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
ClusterIP
When no `type` field is specified in a Service YAML, Kubernetes defaults to `ClusterIP`. This assigns a stable internal IP address reachable only within the cluster, enabling pod-to-pod communication without external exposure. The `spec.type` field is optional, and `ClusterIP` is the implicit default.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
NodePort
Why it's wrong here
NodePort is not the default Service type; it exposes the Service on a static port on every node's IP address, making it reachable from outside the cluster via <NodeIP>:<NodePort>. Because it requires manual node IP and port management, it is not the default. Kubernetes defaults to ClusterIP to keep Services internal by default, and NodePort is typically used for development or simple external access.
- ✓
ClusterIP
Why this is correct
ClusterIP is the default Service type in Kubernetes. When you create a Service without specifying the `type` field, the Kubernetes API server automatically assigns a cluster-internal virtual IP (ClusterIP) that is only reachable from within the cluster. This provides a stable endpoint for pod-to-pod communication and internal load balancing without exposing the Service externally, aligning with the principle of least privilege.
- ✗
LoadBalancer
Why it's wrong here
LoadBalancer is not the default Service type; it provisions an external load balancer from the underlying cloud provider (e.g., AWS ELB, GCP Load Balancer) and automatically creates a NodePort Service to route traffic to the backend pods. This type is intended for exposing Services to the internet, but it incurs additional cloud infrastructure costs and depends on cloud-specific integrations, which is why Kubernetes does not set it as the default.
- ✗
ExternalName
Why it's wrong here
ExternalName is not the default Service type; it maps a Service to an external DNS name using a CNAME record instead of selecting pods. When you use ExternalName, Kubernetes returns the external DNS name to clients, and no cluster IP or proxy is created. This is useful for integrating external services as an internal alias, but it is not the default because it does not provide load balancing or pod selection, which are fundamental to typical Service usage.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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