Question 1

What is Kubernetes and why do teams use it?

Accepted Answer

Kubernetes is a platform that runs and manages containers across many servers. You describe the state you want in YAML, for example three copies of my app, and Kubernetes keeps it that way. It restarts failed containers, spreads them across nodes, scales them, does rolling updates and gives them stable networking. Teams use it so they do not have to manage containers by hand on each server.

Question 2

What is the difference between a Pod, a Deployment and a Service?

Accepted Answer

A Pod is the smallest unit. It runs one or more containers that share network and storage. Pods are temporary and get new IPs when recreated. A Deployment manages a set of identical pods: it keeps the right number running and handles rolling updates and rollbacks. A Service gives those pods one stable name and IP and load balances traffic to them, so other apps do not need to know each pod's address.

Question 3

Explain the main parts of the Kubernetes architecture.

Accepted Answer

The control plane makes the decisions. The API server is the front door every tool talks to, etcd stores the cluster state, the scheduler picks a node for each new pod, and the controller manager runs loops that keep the actual state matching the desired state. Each worker node runs the kubelet, which starts and checks pods, a container runtime like containerd, and kube-proxy, which handles Service networking.

Question 4

What are the different Service types?

Accepted Answer

ClusterIP is the default and is only reachable inside the cluster, which is right for internal services. NodePort opens a port on every node for simple outside access. LoadBalancer asks the cloud for an external load balancer, which is common for public services. ExternalName maps a Service to an outside DNS name. For HTTP traffic we usually put an Ingress in front of ClusterIP services instead of one load balancer per service.

Question 5

A pod is in CrashLoopBackOff. How do you troubleshoot it?

Accepted Answer

CrashLoopBackOff means the container starts, crashes, and Kubernetes keeps restarting it with a growing delay. I run kubectl describe pod to see the events, exit code and restart reason, then kubectl logs, and kubectl logs --previous for the crashed container. Common causes are an app error, a missing config or secret, a wrong command, a failing liveness probe, or OOMKilled when the memory limit is too low. I fix the cause and watch the pod become Ready.

Kubernetes interview questions