Interview Questions

Core Kubernetes Concepts 1. What happens when you run kubectl apply -f deployment.yaml? API server receives request Validates YAML Stores desired state in etcd Scheduler assigns Pod to node Kubelet pulls image & starts container 2. Difference between Deployment, StatefulSet, and DaemonSet? Deployment → stateless apps (web apps) StatefulSet → stateful apps (DBs like MySQL) DaemonSet → runs one pod per node (logging, monitoring agents) 3. What is etcd? Distributed key-value store Stores cluster state (source of truth) 4. What is a Pod? Smallest deployable unit Can have one or multiple containers Shares network + storage 🔹 Networking (Very Important) 5. How does Kubernetes networking work? Each Pod gets unique IP Flat network (no NAT between pods) Uses CNI plugins (Calico, Flannel) 6. Difference between ClusterIP, NodePort, and LoadBalancer? ClusterIP → internal access NodePort → exposes via node IP LoadBalancer → cloud external LB 7. What is Ingress? HTTP/HTTPS routing Works with In...

Docker Interview Questions: 1).🔥 Docker Interview Questions (5+ Years Experience) 1. What is the difference between Docker Image and Container? Answer: * Image → Blueprint (read-only template) * Container → Running instance of image 👉 Example: docker build -t myapp . docker run -d myapp 2. Explain Docker Architecture Answer: * Docker Client * Docker Daemon (dockerd) * Docker Registry (Docker Hub / ECR) * Docker Objects (Images, Containers, Networks, Volumes) 👉 Check: docker info 3. What happens when you run docker run? Answer (Important): 1. Check image locally 2. Pull from registry if not present 3. Create container 4. Setup filesystem (UnionFS) 5. Allocate network 6. Start process 4. Difference: CMD vs ENTRYPOINT Answer: * CMD → Default command (can override) * ENTRYPOINT → Fixed command 👉 Example: CMD ["echo", "Hello"] ENTRYPOINT ["echo"] 5. Multi-stage build – Why? Answer: * Reduce image size * Remove build dependencies 👉 Example: FROM...

1. How do you check system performance? Use multiple tools depending on need: top htop uptime vmstat 1 iostat -x 1 free -m sar -u 1 5 👉 Real-time: CPU bottleneck → check top & vmstat 2. How do you find high CPU consuming process? top ps -eo pid,ppid,cmd,%mem,%cpu --sort=-%cpu | head Kill process: kill -9 3. How do you check memory usage? free -m cat /proc/meminfo top 4. Difference between soft link & hard link? ln file1 hardlink ln -s file1 softlink Hard link → same inode Soft link → pointer (like shortcut) 5. How do you find large files? find / -type f -size +100M du -ah / | sort -rh | head -20 6. How do you monitor logs in real-time? tail -f /var/log/messages tail -f /var/log/syslog 7. What is inode? Check inode: ls -i df -i 👉 Stores metadata of file 8. How do you manage disk space? df -h du -sh * Clean: rm -rf unwanted_files 9. How do you check open ports? netstat -tulnp ss -tulnp 10. How do you check running services? systemctl status nginx systemctl list-units --type=se...

Kubernestes inteview questions for experienced:
 🔥 Kubernetes Interview Questions with Commands 1. How do you check all resources in a cluster? kubectl get all 👉 Namespace specific: kubectl get all -n dev 2. How do you create a resource? kubectl apply -f deployment.yaml 3. How do you check pod details? kubectl describe pod pod-name 4. How do you check pod logs? kubectl logs pod-name 👉 Multi-container pod: kubectl logs pod-name -c container-name 5. How do you exec into a pod? kubectl exec -it pod-name -- /bin/bash 6. How do you check nodes? kubectl get nodes kubectl describe node node-name 7. How do you scale a deployment? kubectl scale deployment app-name --replicas=5 8. How do you check deployment status? kubectl get deployments kubectl describe deployment app-name 9. How do you check rollout status? kubectl rollout status deployment app-name 10. How do you rollback deployment? kubectl rollout undo deployment app-name 11. How do you check services...

Kuberneste interview questions: 1).🔥 Kubernetes Critical Interview Q&A (with Commands) ⚙️ 1. Pod Crash / Debugging Q: Pod is crashing. How do you troubleshoot? kubectl get pods kubectl describe pod kubectl logs kubectl logs --previous kubectl exec -it -- /bin/sh kubectl get events --sort-by=.metadata.creationTimestamp ⚙️ 2. Pod Pending Issue Q: Pod stuck in Pending state kubectl describe pod kubectl get nodes kubectl describe node kubectl get pvc kubectl describe pvc ⚙️ 3. Desired Pods ≠ Running Pods Q: Desired = 5, Running = 3 kubectl get deployment kubectl describe deployment kubectl get rs kubectl get pods -o wide kubectl describe pod kubectl get nodes kubectl top nodes 🌐 4. Service Not Reachable Q: Service is not accessible kubectl get svc kubectl describe svc kubectl get endpoints kubectl get pods -o wide kubectl exec -it -- curl kubectl exec -it -- nslookup 🌐 5. Networking Issue Between Pods kubectl exec -it -- ping kubectl exec -it -- curl ...

Advanced Linux Interview Questions (with Practical Focus) 🧠 1. What happens when you type a command in Linux? Flow: Shell receives command Checks PATH variable Finds binary (/bin, /usr/bin) Forks process Executes via exec() ⚙️ 2. How do you check CPU, Memory, and Disk usage? top htop free -m vmstat iostat df -h du -sh * 👉 Real-time: “If server is slow → first check top and iostat” 🔍 3. How do you find which process is using high CPU? top ps -eo pid,ppid,cmd,%mem,%cpu --sort=-%cpu | head Kill process: kill -9 📂 4. Difference between soft link and hard link? Feature Soft Link Hard Link Command ln -s ln Inode Different Same Works across FS Yes No If original deleted Broken Still works 🔐 5. File permissions (very important) chmod 755 file chown user:group file 👉 755 = rwxr-xr-x 🔥 6. What is inode? Stores metadata of file (size, owner, permissions) Does NOT store filename Check: ls -i df -i 🧪 7. What will you do if disk is full? df -h du -sh /* find / -size +100M 👉 Clear logs: tru...