DevOps Interview Questions – Industry Standard (25 Q&A)

Designed for L2 / L3 DevOps, SRE, Platform Engineer interviews. Covers architecture, CI/CD design, production failures, LAB commands, and field scenarios.

1️⃣ DevOps Fundamentals & Architecture

Q1. Explain DevOps from an enterprise architecture perspective.

Operating model, not a toolset
Git as single source of truth
Automated CI/CD
Infrastructure as Code
Observability-driven feedback

Q2. Scenario: Deployment is successful but users see 500 errors.

Production deployment is green, but customers report application failures.

Check logs
Verify configs & secrets
Validate dependencies
Review dashboards
Rollback if needed

Q3. Explain the CALMS model.

Culture, Automation, Lean, Measurement, Sharing.

Q4. How does DevOps reduce MTTR?

Monitoring → Alert → Runbook → Auto-rollback → Postmortem.

Q5. Common DevOps anti-patterns?

Tool-only DevOps, silos, manual gates, no prod ownership.

2️⃣ CI/CD – Design & Troubleshooting

Q6. Design a CI/CD pipeline for microservices.

Git commit
SAST
Tests
Docker build
Security scan
Staging deploy
Canary / Blue-Green

Q7. LAB: Jenkins logs

kubectl logs jenkins-0 -n jenkins

Q8. Pipeline passes but prod fails?

Missing secrets, env mismatch, wrong image tag, resource limits.

Q9. CI/CD security?

Vault, RBAC, artifact signing, pipeline isolation.

Q10. What is GitOps?

Git defines desired state; systems self-reconcile.

3️⃣ Docker & Containers

Q11. Why containers?

Eliminate drift, speed up delivery.

Q12. LAB: Debug container

docker ps -a
docker logs <id>
docker exec -it <id> /bin/sh

Q13. Works locally, fails in K8s?

Missing ConfigMaps, secrets, wrong limits.

Q14. Optimize images?

Multi-stage builds, slim images.

Q15. Docker networking?

Bridge, Overlay, Host.

4️⃣ Kubernetes

Q16. K8s architecture?

Control plane + worker nodes.

Q17. LAB: Pod debug

kubectl get pods
kubectl describe pod <pod>
kubectl logs <pod>

Q18. Service unreachable?

Selectors, endpoints, ingress, policies.

Q19. Zero downtime?

Rolling updates, probes, replicas.

Q20. StatefulSet vs Deployment?

Stateful DBs vs stateless apps.

5️⃣ Infrastructure as Code

Q21. Why IaC?

Consistency, audit, DR.

Q22. LAB: Terraform

terraform init
terraform plan
terraform apply

Q23. Terraform deleted prod?

Wrong workspace, state issues.

Q24. Traffic spike?

Autoscaling, caching, rate-limit.

Q25. Telecom-grade DevOps?

HA, zero downtime, observability, auto-recovery.

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