Interview Questions

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...

Dokcer Interview Questions: ============================= 🔥 Advanced Practical Docker Interview Questions 🧱 1. Docker Architecture & Internals Q: Explain how Docker works internally when you run docker run nginx. 👉 Expected: Docker CLI → Docker Daemon → containerd → runc Image pull from registry Creation of container using namespaces & cgroups 🐳 2. Write a Dockerfile (Real Scenario) Q: Create a Dockerfile for a Node.js app. FROM node:18-alpine WORKDIR /app COPY package*.json ./ RUN npm install COPY . . EXPOSE 3000 CMD ["npm", "start"] 👉 Follow-up: How to reduce image size? Why use alpine? 📦 3. Multi-Stage Build (Very Important) Q: Optimize this Dockerfile for production. # Build stage FROM node:18 as builder WORKDIR /app COPY . . RUN npm install && npm run build # Production stage FROM nginx:alpine COPY --from=builder /app/build /usr/share/nginx/html 👉 Key concept: Reduce final image size Separate build & runtime 🔐 4. Secrets Handl...

🔥 1. Advanced Linux Basics (Expected Depth) ❓ What happens when you run a command in Linux? 👉 Expected: Shell interprets command Checks PATH Forks process Uses exec() system call Kernel schedules execution ❓ Difference between process and thread? Process = independent memory Thread = shared memory within process ❓ What is load average? 👉 Example: uptime 1 min, 5 min, 15 min CPU load Compare with CPU cores ⚙️ 2. Process Management (Scenario-Based) ❓ A process is consuming 100% CPU. What will you do? 👉 Steps: top / htop ps -ef | grep renice -n 10 -p kill -15 kill -9 ❓ Difference between kill -9 and kill -15? -15 (SIGTERM) → graceful -9 (SIGKILL) → force kill ❓ How to find parent-child process? pstree -p ps -ef --forest 💾 3. Memory Management ❓ How Linux manages memory? 👉 Answer: Physical memory + Swap Virtual memory Paging ❓ What is OOM Killer? 👉 When memory is full → kills high memory process ❓ Check memory usage? free -m vmstat top 📂 4. File System & Storage ❓ Differenc...

linux interview questions: ========================= Critical Linux Interview Questions (Experienced) 🧠 1. Troubleshooting Scenarios (MOST IMPORTANT) 👉 Q1: Server is slow. How will you troubleshoot? Expected Approach: Check CPU: top / htop Check Memory: free -m Check Disk: df -h du -sh /* Check processes: ps -ef --sort=-%cpu Check I/O: iostat 👉 Q2: Disk is full. What will you do? Answer: df -h du -sh /* | sort -hr Clean logs: /var/log Remove old files Use logrotate 👉 Q3: System not booting. How to recover? Answer: Boot into rescue mode / single-user mode Fix: /etc/fstab GRUB issues Reinstall bootloader: grub2-install 👉 Q4: Service is not starting. What to check? systemctl status journalctl -xe Check config files Check port conflicts: netstat -tulnp 👉 Q5: High CPU usage. How to fix? top ps -eo pid,ppid,cmd,%mem,%cpu --sort=-%cpu Kill process: kill -9 ⚙️ 2. Process & Resource Management 👉 Q6: Difference between nice and renice? nice: start process with priority renice: chan...

terraform Interview Questions: ============================== 1).Terraform Practical Interview Questions (Experienced) 1. Real-time Scenario Questions 👉 Q1: You have created infrastructure manually in AWS. Now you need to bring it under Terraform. How will you do it? Expected Answer: Use terraform import Write resource block first Import using: terraform import aws_instance.myec2 i-1234567890 Run terraform plan to verify 👉 Q2: You deleted a resource manually in AWS, but Terraform state still has it. What will you do? Answer: Run: terraform refresh OR terraform apply Terraform will recreate the resource 👉 Q3: How will you handle multiple environments (dev, qa, prod)? Answer: Use: Workspaces Separate backend configs .tfvars files Example: terraform workspace new dev terraform workspace select dev 👉 Q4: How do you manage secrets in Terraform? Answer: Use: AWS Secrets Manager HashiCorp Vault Environment variables Avoid hardcoding in .tf files 👉 Q5: How do you handle remote state? Ans...

Docker Interview Questions: =========================== Docker interview questions: ================================ 18. How do you troubleshoot a failing container? * Check logs: docker logs * Inspect container: docker inspect * Exec into container: docker exec -it ================================================== 17. What is Docker Registry? A storage for Docker images (e.g., Docker Hub). ============================================== . How will you deploy a microservice using Docker + Kubernetes? ✅ Answer (structured & practical) First, I containerize the application using Docker. Step 1: Create Docker Image * Write a Dockerfile * Build image: docker build -t myapp:v1 . * Push to registry: docker push myrepo/myapp:v1 Step 2: Create Kubernetes Deployment Define a Deployment YAML: apiVersion: apps/v1 kind: Deployment metadata: name: myapp-deployment spec: replicas: 3 selector: matchLabels: app: myapp template: metadata: labels: app: ...

Aws Inteview questions: ===================== Aws Interview Questions: ============================= 1. Core AWS Concepts (Must Know) Q1: What is AWS Global Infrastructure? 👉 AWS consists of: * Regions * Availability Zones (AZs) * Edge Locations (CloudFront) 👉 Example: * Region → ap-south-1 (Mumbai) * AZ → ap-south-1a, 1b Q2: Difference between Region and Availability Zone? * Region = Geographical area * AZ = Isolated data centers inside a region Q3: What is IAM? Best practices? * Identity and Access Management * Controls access to AWS services ✅ Best Practices: * Use roles instead of access keys * Enable MFA * Follow least privilege principle 🔹 2. EC2 (Compute) Q4: What are EC2 instance types? * General purpose → t3, t2 * Compute optimized → c5 * Memory optimized → r5 * Storage optimized → i3 Q5: Difference between Spot, On-Demand, and Reserved Instances? Type Use Case On-Demand Short-term workloads Reserved Long-term, predictable Spot Cost saving (can be interrupted) Q6: Wha...