💥 DevOps Engineer Interview Experience – Deep Dive with Real Questions & Answers

If you're preparing for a DevOps Engineer role or actively interviewing, this post is for you. I recently went through a multi-round DevOps interview, and it challenged everything — from my core fundamentals to advanced cloud architecture decisions. 🚀

Here’s a full breakdown of the experience, along with real questions I was asked and how I answered them — shared to help other DevOps professionals succeed.

✅ Round 1: Technical Screening (30 minutes)

This round was about understanding my current experience, tools, and general Linux + cloud knowledge.

🔹 Questions I Was Asked:

1. Walk me through your current project and architecture.

I explained how we use AWS (EKS for Kubernetes), deploy via Helm charts, manage infra using Terraform, and monitor with Prometheus + Grafana. My role involves building CI/CD pipelines, automating infrastructure provisioning, and responding to incidents.

2. Which DevOps tools have you worked with in the last 2 years?

Jenkins, GitHub Actions, Docker, Terraform, Ansible, AWS CLI, Prometheus, ELK Stack, and Vault.

3. What AWS services have you used in production?

EC2, S3, VPC, IAM, EKS, CloudWatch, ALB, Route 53, SSM, and RDS.

4. How do you expose a Kubernetes application to the internet?

Using Service of type LoadBalancer or via Ingress Controller like NGINX, often with DNS routing through Route 53.

5. What is a NAT Gateway, and why do we need it?

It's used to allow instances in a private subnet to access the internet for package updates or API calls without exposing them publicly.

6. How to check running processes in Linux?

ps aux | less
top
htop
        

7. Command to find files larger than 100MB?

find / -type f -size +100M
        

8. Difference between Deployment and StatefulSet in K8s?

Deployments are for stateless apps, while StatefulSets manage stateful workloads like databases with persistent identity and storage.

9. ConfigMap vs Secret?

ConfigMaps store non-sensitive config data, Secrets store sensitive data (like passwords), encrypted at rest.

10. How to check network connectivity between two servers?

ping <ip>
telnet <ip> <port>
nc -zv <ip> <port>
        

11. CI/CD pipeline experience?

Built GitHub Actions pipelines that run tests, build Docker images, deploy via Helm, and auto-trigger Terraform infra changes — with rollback and Slack alerts.

✅ Round 2: Technical Deep Dive (60 minutes)

This round pushed me into real-world problem solving, design decisions, and DevOps best practices.

🔸 Real Questions and My Approach:

1. Cross-account S3 access (Account A → Bucket in Account B)?

Use a bucket policy in Account B and an IAM role in Account A with sts:AssumeRole. Attach a trust policy and provide access via role assumption.

2. Write a multi-stage Dockerfile for Node.js app:

# Build Stage
FROM node:18-alpine AS builder
WORKDIR /app
COPY . .
RUN npm ci && npm run build

# Final Stage
FROM node:18-alpine
WORKDIR /app
COPY --from=builder /app/dist ./dist
RUN npm ci --only=production
CMD ["node", "dist/index.js"]
        

3. Terraform state file is corrupted. What now?

Restore from .terraform/ or use versioned S3 remote state. Use terraform state pull or recover from backup.

4. Private EC2 needs internet access without NAT Gateway?

Use:

• VPC endpoints (S3, EC2, etc.)
• Bastion Host with proxy
• SSM Session Manager

5. Debug a container that exited immediately:

docker ps -a
docker logs <container_id>
docker inspect <container_id>
        

6. Import existing AWS VPC into Terraform:

terraform import aws_vpc.myvpc vpc-12345678
        

7. Implement Blue-Green deployment in Kubernetes?

Use separate versions of the app, shift traffic using labels, or tools like Argo Rollouts or Ingress routing strategies.

8. Secret management in Terraform?

Never hardcode secrets. Use:

• Environment variables
• HashiCorp Vault
• SOPS with GitOps
• Remote state encryption

9. Difference: COPY vs ADD in Dockerfile?

COPY is safer, only copies files. ADD can unpack archives and fetch URLs.

10. Provision AWS resources across accounts using Terraform?

Use provider with alias and assume_role block for cross-account setup.

11. How to handle secrets in Docker PHP app (MySQL creds)?

Use Docker secrets, environment variables via .env, or an external secret store (Vault/AWS Secrets Manager).

12. S3 created by Terraform, but someone added policy manually — now what?

Use terraform plan to detect drift. Optionally import or modify config to match the manual change or revert it.

13. Kubernetes network policies (restrict traffic):

apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
spec:
  podSelector:
    matchLabels:
      app: frontend
  ingress:
  - from:
    - podSelector:
        matchLabels:
          app: backend
        

14. Python script to back up files older than 30 days:

import os, shutil, time

source = "/data"
backup = "/backup"
now = time.time()

for file in os.listdir(source):
    path = os.path.join(source, file)
    if os.path.isfile(path) and os.stat(path).st_mtime < now - 30*86400:
        shutil.copy2(path, backup)
        

15. Cloud cost optimization strategies?

• Rightsize instances
• Stop unused resources
• Use spot or savings plans
• Apply lifecycle policies
• Monitor with Cost Explorer

16. How to set up geo-location-based routing in AWS?

Use Route 53's geolocation routing policy with different DNS records for each region.

17. Production issue: 503 errors, ImagePullBackOff, Pod evictions. What now?

Troubleshooting:

• kubectl describe + logs
• Check image pull secrets, disk pressure, memory
• Inspect node taints, quotas, liveness/readiness probes

Prevention:

• Pre-pull images
• Resource limits
• Alerting via Prometheus
• Pod disruption budgets

✅ Round 3: Behavioral Round

This was about mindset, adaptability, and ownership.

💬 Sample Questions:

1. How do you approach new technologies with zero experience?

I start with documentation, official tutorials, and apply it in test environments before suggesting real use cases.

2. Tight deadline with limited resources?

Shared a real example of deploying a secure CI/CD pipeline within 24 hours during a product release.

3. Mistake in production and how you handled it?

I missed a CIDR rule in a security group which blocked traffic. I identified it via logs, fixed it, and added a checklist step for future changes.

4. Most difficult technical challenge?

Migrating from legacy monolith to Kubernetes (EKS) — handled DB migration, traffic splitting, and zero-downtime deployment.

5. How do you convince stakeholders to adopt a new process?

Show them a proof-of-concept, share results, and compare performance & cost benefits.

6. When did you learn a tool quickly to solve a problem?

I learned HashiCorp Vault in 2 days to secure DB credentials in our Terraform deployments.

💡 Final Takeaways

✨ DevOps interviews test:

• Depth of real-world experience
• Practical problem-solving
• Solid AWS/Linux/Kubernetes/Terraform knowledge
• How you communicate under pressure

👉 My advice: Don't just learn commands. Learn context. Practice real-world scenarios.

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