Linux interview Questions :

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: What is Auto Scaling? 👉 Automatically adjusts EC2 instances based on load Types: * Dynamic scaling * Scheduled scaling Q7: What is Load Balancer? * Distributes traffic across instances Types: * ALB (Layer 7) * NLB (Layer 4) * CLB (Legacy) 🔹 3. VPC & Networking (VERY IMPORTANT 🔥) Q8: What is VPC? 👉 Virtual Private Cloud → isolated network Q9: Difference between Public and Private Subnet? Public Subnet Private Subnet Has Internet Gateway No direct internet Used for web servers Used for DB Q10: What is NAT Gateway? 👉 Allows private subnet instances to access internet (outbound only) Q11: Difference between Security Group and NACL? Security Group NACL Stateful Stateless Instance level Subnet level Allow rules only Allow + Deny 🔹 4. Storage Services Q12: Difference between S3, EBS, and EFS? Service Type S3 Object storage EBS Block storage EFS File storage Q13: What are S3 storage classes? * Standard * Intelligent-Tiering * Glacier * Glacier Deep Archive Q14: What is Versioning in S3? 👉 Keeps multiple versions of objects 🔹 5. Databases Q15: Difference between RDS and DynamoDB? RDS DynamoDB Relational NoSQL Fixed schema Flexible SQL support Key-value Q16: What is Multi-AZ in RDS? 👉 High availability (failover) Q17: What is Read Replica? 👉 Used for read scaling 🔹 6. DevOps & Automation (Your Strong Area 💪) Q18: What is CloudFormation vs Terraform? CloudFormation Terraform AWS native Multi-cloud JSON/YAML HCL Q19: What is CI/CD in AWS? Tools: * CodePipeline * CodeBuild * CodeDeploy Q20: How do you deploy applications using AWS? 👉 Example flow: * Code → Git * Build → CodeBuild * Deploy → EC2 / ECS / EKS 🔹 7. Monitoring & Logging Q21: What is CloudWatch? 👉 Monitoring service Features: * Metrics * Logs * Alarms Q22: Difference between CloudWatch and CloudTrail? CloudWatch CloudTrail Performance monitoring API logging Metrics & logs Audit 🔹 8. Security (VERY IMPORTANT 🔐) Q23: What is KMS? 👉 Key Management Service for encryption Q24: How do you secure S3 bucket? * Block public access * IAM policies * Bucket policies * Encryption Q25: What is Shared Responsibility Model? 👉 AWS secures: * Infrastructure 👉 You secure: * Data * OS * Applications 🔹 9. Scenario-Based Questions (IMPORTANT 🔥🔥) Q26: 👉 Website is slow. What will you do? * Use CloudFront * Enable Auto Scaling * Use ALB * Optimize DB Q27: 👉 Design highly available architecture * Multi-AZ * Load Balancer * Auto Scaling * RDS Multi-AZ Q28: 👉 How to migrate on-prem to AWS? * Lift & Shift * Re-platform * Re-architect 🔹 10. Advanced (For 5+ Years Experience) Q29: What is EKS vs ECS? * EKS → Kubernetes * ECS → AWS native Q30: What is Lambda? 👉 Serverless compute Q31: What is Step Functions? 👉 Workflow orchestration ===================================== 🔥 1. Pod & Deployment (Hands-on) Q1: 👉 Create a deployment with 3 replicas using nginx Answer (commands): kubectl create deployment nginx-deploy --image=nginx kubectl scale deployment nginx-deploy --replicas=3 Q2: 👉 Update image version without downtime kubectl set image deployment/nginx-deploy nginx=nginx:1.25 kubectl rollout status deployment nginx-deploy Q3: 👉 Rollback deployment kubectl rollout undo deployment nginx-deploy Q4: 👉 Check why pod is not running kubectl describe pod kubectl logs 🔥 2. Debugging & Troubleshooting (VERY IMPORTANT) Q5: 👉 Pod stuck in CrashLoopBackOff — what will you do? ✔ Steps: kubectl logs kubectl describe pod 👉 Check: Wrong image App crash Missing env variables Port issues Q6: 👉 Pod is in Pending state ✔ Check: kubectl describe pod 👉 Possible reasons: No resources Node not available PVC not bound Q7: 👉 Node is NotReady — what will you do? ✔ Steps: kubectl get nodes kubectl describe node 👉 Check: kubelet status disk/memory pressure network issues 🔥 3. Networking (Real-Time) Q8: 👉 Expose deployment as service kubectl expose deployment nginx-deploy --type=NodePort --port=80 Q9: 👉 Difference between ClusterIP, NodePort, LoadBalancer? ClusterIP → internal NodePort → external via node LoadBalancer → cloud LB Q10: 👉 Pod cannot access another pod ✔ Debug: kubectl exec -it -- curl 👉 Check: Service name DNS Network policy 🔥 4. ConfigMaps & Secrets Q11: 👉 Create ConfigMap and use in pod kubectl create configmap app-config --from-literal=env=prod Q12: 👉 Create Secret kubectl create secret generic db-secret --from-literal=password=1234 🔥 5. Storage (PVC/PV) Q13: 👉 Create PVC apiVersion: v1 kind: PersistentVolumeClaim metadata: name: pvc-demo spec: accessModes: - ReadWriteOnce resources: requests: storage: 1Gi 👉 Apply: kubectl apply -f pvc.yaml Q14: 👉 Pod not mounting volume — debug steps? ✔ Check: kubectl describe pvc kubectl describe pod 🔥 6. Logs & Monitoring Q15: 👉 Check logs of multi-container pod kubectl logs -c Q16: 👉 Access pod shell kubectl exec -it -- /bin/bash 🔥 7. Security (Important 🔐) Q17: 👉 Limit pod resources resources: requests: memory: "64Mi" cpu: "250m" limits: memory: "128Mi" cpu: "500m" Q18: 👉 What is RBAC? ✔ Role + RoleBinding kubectl create role pod-reader --verb=get,list --resource=pods 🔥 8. Advanced (Experienced Level) Q19: 👉 What is Helm? Why use it? Package manager for Kubernetes Reusable templates Q20: 👉 What is HPA (Horizontal Pod Autoscaler)? kubectl autoscale deployment nginx-deploy --cpu-percent=50 --min=1 --max=10 Q21: 👉 What is StatefulSet? 👉 Used for: Databases Stable hostname Persistent storage 🔥 9. Real Scenario Questions (VERY IMPORTANT 💥) Q22: 👉 Application not accessible from browser ✔ Steps: Check pod Check service Check ingress Check security group Q23: 👉 High CPU usage in pods ✔ Solution: Increase limits Enable HPA Optimize app Q24: 👉 Deployment failed after update ✔ Fix: kubectl rollout undo deployment