What are the main components of a Kubernetes cluster (control plane and nodes)?
What they are really testing: Whether you know the moving parts and their roles, which is essential for debugging. They want the control-plane vs node split and what each piece does.
A real interview question
What are the main components of a Kubernetes cluster (control plane and nodes)?
What most people say
drag me
“There is a master node and worker nodes, and the workers run the containers.”
Outdated "master" framing and no detail. It cannot name the API server, etcd, scheduler, kubelet, or kube-proxy, so it gives no foothold for diagnosing where something broke.
The follow-ups they ask next
Why is etcd so important, and what follows from that?
It stores all cluster state, so it must be highly available and backed up. Losing etcd without a backup means losing the cluster definition; corruption or split-brain causes serious outages.
What is the kubelet responsible for?
On each node it takes pod specs from the API server, ensures those containers are running and healthy, and reports status back. If the kubelet is down, the node goes NotReady.
What the interviewer is listening for
- Names API server, etcd, scheduler, controller-manager
- Knows kubelet/kube-proxy/runtime on nodes
- Connects components to debugging
What sinks the answer
- Only "master and workers"
- Cannot name etcd or the API server
- No idea what the kubelet does
If you genuinely do not know
Say this instead of freezing. Reasoning out loud from what you do know beats silence every single time, and a good interviewer is listening for exactly that.
“Control plane: [API server (the front door), etcd (the state store), scheduler (places pods), controller-manager (reconciliation loops)]. Nodes: [kubelet (runs/reports pods), kube-proxy (service networking), a runtime like containerd]. Knowing this split [tells me where to look when something breaks].”
Keep going with kubernetes
Foundation
What problem does Kubernetes solve, and what does it actually do for you?
Foundation
What is a Pod, and why do you use a Deployment instead of creating Pods directly?
Foundation
What is a Service in Kubernetes, and what are the main types?
Junior
When would you use a Deployment versus a StatefulSet versus a DaemonSet?
Junior
How do you inject configuration and secrets into a pod, and what is the catch with Kubernetes Secrets?
Junior
What is the difference between liveness, readiness, and startup probes?
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