How to Ace the DevOps Technical Screening in 2026

The technical screening happens before the full interview loop and decides if you get to the real rounds. Here's what's in it and how to pass it.

What the DevOps Technical Screen Usually Looks Like

Most companies use one of these formats:

1. 30-min phone screen — 3–5 questions, conversational, tests depth not breadth
2. Take-home task (2–4 hours) — write a Dockerfile, CI/CD pipeline, or Terraform config
3. HackerRank/Codility screen — Linux commands, shell scripting, sometimes basic coding
4. Live coding/debugging — share screen, debug a broken Kubernetes YAML or Bash script

All of them test the same things: can you actually do the job?

The 10 Most Common Phone Screen Questions

These come up in almost every DevOps phone screen:

1. "Walk me through what happens when a pod fails in Kubernetes."

Bad answer: "Kubernetes restarts it."

Good answer: "The kubelet detects the container exit via liveness probe or exit code. If the restart policy is Always (the default), the kubelet restarts the container. After repeated failures, Kubernetes applies exponential backoff — 10s, 20s, 40s up to 5 minutes. That's the CrashLoopBackOff state. To debug: I'd check kubectl describe pod for events, then kubectl logs --previous to see the last container's output."

2. "How does a request flow from the browser to a pod in Kubernetes?"

Expected path: Browser → DNS → Load Balancer (NLB/ALB) → Ingress Controller → Service → Pod. Be ready to explain each hop and what can fail at each step.

3. "What's the difference between a rolling update and a blue-green deployment?"

Rolling: gradually replaces old pods with new ones. Some users see old version, some see new version during the rollout. Zero-downtime if health checks are configured properly.

Blue-green: run two identical environments. Traffic switches all-at-once from blue to green. Easy rollback — switch back. Costs double the compute during transition.

4. "How do you debug a Terraform plan that's unexpectedly destroying a resource?"

Walk through: check if state is out of sync (terraform state list), check if resource was imported (terraform show), check if someone manually changed the resource in the console, look at the plan diff carefully for what triggered the replacement (forces replacement in plan output). Use terraform plan -target=resource to isolate.

5. "Explain the CI/CD pipeline at your last job."

Have a story: source → trigger → build → test → artifact → deploy → verify. Be specific: "GitHub Actions, triggered on merge to main, builds and pushes Docker image to ECR with the commit SHA as tag, deploys to EKS via ArgoCD which watches the Helm values file in the GitOps repo..."

How to Pass a Take-Home DevOps Task

Most take-home tasks look like:

• "Write a Dockerfile for this Python app and optimize it"
• "Write a GitHub Actions pipeline for this repo"
• "Write Terraform to provision an ECS cluster on AWS"

What they're evaluating:

1. Does it actually work?
2. Is it production-quality or "just make it pass"?
3. Can you explain your decisions?

Dockerfile task checklist:

• Multi-stage build (dev dependencies don't go to production)
• Non-root user
• Specific base image version (not latest)
• .dockerignore file included
• Package lock file copied before source code (cache optimization)
• Minimal final image (alpine or distroless)

CI/CD task checklist:

• Trigger on correct events (PR and merge to main)
• Secrets as GitHub Secrets, not hardcoded
• Caching dependencies
• Test step before build step
• Lint before tests
• Image tagged with commit SHA

Terraform task checklist:

• Remote state configured (S3 + DynamoDB)
• Variables file, not hardcoded values
• Separate files: main.tf, variables.tf, outputs.tf
• Proper naming (environment prefix on all resources)
• README explaining how to apply

Linux / Shell Screening Tips

Many companies use HackerRank for shell scripting. Practice these:

# Find and kill processes
ps aux | grep nginx
kill -9 $(pgrep nginx)
 
# Find large files
find /var -type f -size +100M
 
# Monitor log file in real time and grep for errors
tail -f /var/log/app.log | grep -i error
 
# Count unique IPs in access log
awk '{print $1}' access.log | sort | uniq -c | sort -rn | head -10
 
# Check which process is using a port
ss -tlnp | grep :8080
lsof -i :8080
 
# CPU and memory of a process
ps aux | grep myapp
top -p $(pgrep myapp)
 
# Disk usage breakdown
du -sh /var/* | sort -rh | head -10

What Interviewers Actually Judge You On

Depth over breadth. Knowing 20 tools shallowly is worth less than knowing 5 tools deeply. When you say "I've used Prometheus" — be ready to explain Prometheus' scrape model, TSDB storage, PromQL, and how to debug a target that's down.

Production experience signals. Stories that start with "in production, we had..." immediately signal you've dealt with real problems. Anyone can read docs. Not everyone has debugged OOMKills at 2am.

Knowing what you don't know. "I haven't used Tekton specifically but it's similar to Jenkins Pipelines in concept — I'd approach it by..." is a great answer. Saying you know something you don't will be exposed.

Communication clarity. DevOps engineers interact with developers, SREs, security, and management. Explaining technical things clearly is a core part of the job.

2-Week Prep Plan

Week 1:

• Day 1–2: Revise Kubernetes fundamentals (pod lifecycle, networking, RBAC)
• Day 3–4: Terraform (state, modules, remote backend)
• Day 5–6: CI/CD (write a full pipeline from scratch)
• Day 7: Linux commands + shell scripting practice

Week 2:

• Day 1–2: AWS (VPC, EKS, IAM, S3)
• Day 3–4: Monitoring (Prometheus, Grafana, alerting)
• Day 5: Practice answering common questions out loud
• Day 6–7: Do a mock take-home task (write a full Dockerfile + CI pipeline for a sample app)

The One Thing That Sets Good Candidates Apart

Operational thinking. When you're asked "how would you deploy this?" — the best answers mention not just how to deploy, but how to verify it's healthy, how to roll back if it breaks, and how to know if it's slow.

That mindset — deploy, verify, monitor, rollback — is what companies are hiring for. Show it in every answer.