Kubernetes · Orchestration under pressure
What is a node and what does kubelet do?
Short answer
A node is a machine that runs pods. Kubelet watches assigned pods, tells the container runtime to start them, runs probes and reports status back to the API server.
Nodes are the data plane. Each one runs kubelet, a container runtime such as containerd, and a networking implementation. Kubelet does not schedule pods; it only runs pods that the control plane has assigned to its node. It also enforces pod resource settings and reports conditions such as memory pressure and disk pressure.
- Kubelet registers the node and sends heartbeats through Lease objects
- The runtime pulls images and manages container lifecycle
- The CNI plugin gives pods IP addresses and connectivity
- kube-proxy or an eBPF dataplane implements Service traffic
- Node conditions and taints control what can be scheduled there
kubectl get nodes
kubectl describe node worker-1
kubectl top node worker-1Nodes are cattle, not pets. Treat them as replaceable, keep bootstrap automated, and avoid storing state on local disks unless the workload explicitly owns that lifecycle. In managed clusters, node upgrades still require attention to disruption budgets and capacity headroom.
Follow-ups you should expect
Interviewers use these to check whether the first answer was understanding or memorisation.
- 1What is the difference between capacity and allocatable?
- 2What happens when kubelet cannot reach the API server?
- 3Who schedules pods, kubelet or the scheduler?
- 4How do you safely drain a node?
Say it in the interview
A node is a worker machine, and kubelet is its agent. It watches for pods bound to the node, asks the runtime to start containers, runs probes and reports status and resource usage. Networking and Service routing are handled by the CNI and kube-proxy or an eBPF dataplane. I treat nodes as disposable and rely on requests, taints and disruption budgets to keep drains safe.
Use this as a model, not a script. Saying it in your own words is what makes it survive follow-up pressure.
Related questions
Reading is step one
Now say it out loud.
Understanding an answer and delivering it under pressure are different skills. Rehearse this topic in a live Kubernetes mock interview and get scored feedback on depth, clarity and confidence.