How to Crack a DevOps Interview in 30 Days (2026 Plan)

Most DevOps interview prep fails because it's unfocused — you watch random YouTube videos, do a Kubernetes tutorial, then freeze when asked "how does etcd work?" This 30-day plan is structured, practical, and built around what interviewers actually ask.

Who This Is For

• Freshers applying for their first DevOps role
• 1-2 year developers transitioning to DevOps
• SysAdmins moving into cloud/DevOps

Not required: Deep expertise in everything. You need solid fundamentals in 4-5 areas and real project examples.

What DevOps Interviews Actually Test

Most interviews have 3 rounds:

1. Technical screening (30 min) — basics: Docker, Linux, CI/CD concepts
2. Deep technical (60-90 min) — Kubernetes, cloud, troubleshooting scenarios
3. System design / practical (60 min) — "Design a CI/CD pipeline for this app"

The trap: most candidates over-prepare on theory and under-prepare on practical problem-solving.

Week 1 (Days 1-7): Core Foundations

Day 1-2: Linux + Bash

Must-know commands:

# Process management
ps aux | grep nginx
kill -9 <pid>
systemctl status nginx
 
# Disk/memory
df -h
du -sh /var/log/*
free -m
top / htop
 
# Networking
netstat -tulpn
ss -tlnp
curl -I https://example.com
traceroute / dig / nslookup
 
# File operations
find /etc -name "*.conf" -mtime -7
grep -r "ERROR" /var/log/ | tail -20
awk '{print $1}' access.log | sort | uniq -c | sort -rn

Practice: Set up a Linux VM (free: VirtualBox, WSL2, or Oracle Cloud free tier). Do 30 minutes of CLI practice daily.

Day 3-4: Docker

Must-know concepts:

• Image vs Container vs Layer
• Dockerfile best practices (multi-stage, non-root, COPY vs ADD)
• docker compose networking (service names, not localhost)
• docker volume vs bind mount
• How to debug a container that keeps restarting

# Common interview commands
docker build -t app:v1 --no-cache .
docker run -d -p 8080:80 --name web nginx
docker exec -it web /bin/sh
docker logs web --follow
docker inspect web | grep IPAddress
docker stats

Practice: Dockerize a simple Python/Node app. Debug an intentionally broken Dockerfile.

Day 5-6: Git + GitHub

• git rebase vs merge (know the difference clearly)
• git cherry-pick, git stash
• Branch protection rules
• PR review workflow
• Resolving merge conflicts

The interview question: "Walk me through your Git branching strategy" — answer: GitFlow or trunk-based development with feature flags.

Day 7: Review + Mock Questions

Run through 20 basic questions from devopsboys.com/interview-prep.

Week 2 (Days 8-14): Kubernetes

This is where most interviews go deep. You need to go beyond basics.

Day 8-9: Core Objects

• Pod, Deployment, Service, Ingress
• ConfigMap, Secret
• Namespace, ResourceQuota, LimitRange
• Practice: Deploy a 3-tier app (frontend + backend + database) on minikube

Day 10-11: Scheduling + Autoscaling

• Node affinity, taints/tolerations
• Resource requests/limits (why they matter)
• HPA — how it uses metrics-server
• VPA, Cluster Autoscaler, Karpenter basics

Day 12-13: Troubleshooting (critical)

Practice these scenarios until they're instinct:

# Scenario: pod stuck in Pending
kubectl describe pod <name>   # read the Events section
# → No nodes available: check resources, taints, node selectors
 
# Scenario: CrashLoopBackOff
kubectl logs <pod> --previous
# → Read the last crash logs
 
# Scenario: ImagePullBackOff
kubectl describe pod <name>
# → Check image name, registry auth, network
 
# Scenario: Service not routing traffic
kubectl get endpoints <service>
# → Empty endpoints = selector mismatch

Day 14: RBAC + Security

• Role vs ClusterRole vs RoleBinding
• Service Account and when to use it
• Network Policies (allow/deny traffic)
• Pod Security Standards

Week 3 (Days 15-21): Cloud (AWS Focus)

Day 15-16: Core AWS Services

Must-know for DevOps roles:

• EC2: instance types, AMI, Security Groups, user data
• VPC: subnets (public/private), NAT Gateway, Internet Gateway, route tables
• IAM: roles vs users, policies, instance profiles, OIDC
• S3: versioning, lifecycle policies, bucket policies
• RDS: Multi-AZ vs Read Replica

Day 17-18: EKS

• How EKS node groups work (managed vs self-managed)
• IRSA (IAM Roles for Service Accounts)
• EKS add-ons (CoreDNS, kube-proxy, VPC CNI)
• ALB Ingress Controller
• Common issues: nodes NotReady, pods Pending

Day 19-20: CI/CD with GitHub Actions

Build this pipeline mentally (be ready to draw it):

Push to main
  → Run tests
  → Build Docker image
  → Push to ECR
  → Deploy to EKS via kubectl/Helm/ArgoCD
  → Notify Slack

Know: secrets management, matrix builds, reusable workflows, OIDC authentication to AWS.

Day 21: Terraform

• State file + remote state (S3 + DynamoDB)
• Modules, variables, outputs
• Plan vs Apply
• How to handle drift
• Common: "We have existing infra not in Terraform, how do you import it?"

Week 4 (Days 22-28): System Design + Behavioral

Day 22-23: Design Questions

Practice answering these out loud:

"Design a CI/CD pipeline for a microservices app"

Answer structure:
1. Source: GitHub with branch protection
2. CI: GitHub Actions — test, build, scan (Trivy), push to ECR
3. CD: ArgoCD watching Helm charts repo
4. Environments: dev (auto-deploy) → staging (auto) → prod (manual gate)
5. Monitoring: Prometheus + Grafana + PagerDuty alerts
6. Rollback: ArgoCD rollback or Helm rollback

"Production is down at 2 AM — walk me through your response"

1. Check monitoring dashboard (Grafana)
2. kubectl get pods -A | grep -v Running
3. Check recent deployments (ArgoCD/Helm history)
4. Check logs of failing pods
5. Rollback if recent deploy caused it
6. Post-mortem after resolution

Day 24-25: Monitoring + Observability

• Prometheus architecture (scrape-based)
• PromQL basics: rate(), increase(), histogram_quantile()
• Grafana dashboards
• Alert rules + Alertmanager routing
• Loki for logs, Jaeger/Tempo for traces

Day 26-27: Security + GitOps

• Container image scanning (Trivy)
• Secrets management (Vault vs AWS Secrets Manager)
• GitOps principles — ArgoCD/Flux
• SBOM, SLSA supply chain

Day 28: Behavioral Questions

STAR format (Situation, Task, Action, Result) for:

• "Tell me about a production incident you handled"
• "Describe a time you improved deployment speed"
• "How did you reduce cloud costs?"

Prepare 3-4 real stories from your experience.

Days 29-30: Final Prep

Day 29: Full Mock Interview

Do a complete 60-minute mock:

• 10 min: Linux/Docker questions
• 20 min: Kubernetes troubleshooting scenario
• 20 min: System design question
• 10 min: Behavioral

Record yourself. Watch it back. Painful but effective.

Day 30: Rest + Review Weak Areas

Don't cram. Review your notes, practice 10 questions from areas you're weakest on.

Interview Day Tips

On troubleshooting questions: Always start with kubectl describe and kubectl logs. Say "I'd check the Events section first." Interviewers want to see your process.

On "I don't know": Say "I haven't used that specifically, but based on my experience with X, I'd approach it by..." — shows thinking pattern.

On system design: Draw boxes and arrows. Explain trade-offs. "I'd use X because Y, but Z is an alternative if..."

Questions to ask them: "What does your incident response process look like?" / "What's the biggest infra challenge you're solving right now?" — shows genuine interest.

Resources

• devopsboys.com/interview-prep — 350+ DevOps interview questions
• KodeKloud DevOps Path — hands-on labs for every topic above
• CKA on Udemy — Kubernetes deep dive