Interview › Kubernetes, Docker, Helm & Podman
What is a Service, and what are the types (ClusterIP, NodePort, LoadBalancer, ExternalName)?
Kubernetes, Docker, Helm & Podman · Basic level
Answer
A Service gives Pods a stable virtual endpoint and load-balances to matching endpoints. ClusterIP is internal, NodePort exposes a port on each node, LoadBalancer provisions an external load balancer through the cloud provider, and ExternalName returns a DNS CNAME to an external service.
Technical explanation
Services target EndpointSlices, not just Pods directly, and the control plane updates those endpoints as Pods become ready or unready.
NodePort and LoadBalancer expose traffic differently; cloud LoadBalancer behavior depends on provider/controller implementation.
Kubernetes resources are declarative API objects; controllers continuously drive actual state toward spec.
The practical interview angle is to connect the concept to reliability: scheduling, healing, scaling, rollout safety, and clear ownership.
Use kubectl get, describe, explain, and -o yaml to move from high-level view to exact spec/status details.
Hands-on example
1. Create a local lab with kind or minikube, then use it to demonstrate: create ClusterIP, NodePort, and LoadBalancer-style Service manifests and compare behavior.
2. Run kubectl get nodes -o wide, kubectl get pods -A, kubectl describe, and kubectl get -o yaml to connect the concept to actual cluster state.
3. Make one intentional change, such as a label change, image update, or replica change, and watch how the control plane reconciles it.
4. Capture the command output and convert it into an interview story: desired state, observed state, failure mode, and fix.
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More Kubernetes, Docker, Helm & Podman interview questions
- What is Kubernetes, and what problem does it solve over running containers manually?
- Explain the Kubernetes control plane components (API server, etcd, scheduler, controller manager).
- What runs on a worker node (kubelet, kube-proxy, container runtime)?
- What is a Pod, and why does Kubernetes schedule Pods rather than containers?
- What is the difference between a Pod, a ReplicaSet, and a Deployment?
- How does a Deployment perform a rolling update, and how do maxSurge and maxUnavailable work?
- How do you roll back a Deployment, and how does Kubernetes track revisions?
- How does a Service select its Pods, and what happens if labels do not match?