Top 50 DevOps Engineer Interview Questions & Answers 2026

Here are the Top 50 DevOps Engineer Interview Questions & Answers for 2026 — updated to cover today’s most-asked topics, from CI/CD and Kubernetes to GitOps, observability, security, and platform engineering. Use this as your go-to revision sheet before any DevOps interview.

DevOps Fundamentals

1. What is DevOps?
   DevOps is a culture and set of practices that unite software development (Dev) and IT operations (Ops) to shorten the delivery lifecycle and provide continuous, reliable software delivery through automation, collaboration, and feedback.
2. What are the key benefits of DevOps?
   Faster time to market, higher deployment frequency, lower failure rate of releases, faster recovery from incidents, and better collaboration between teams.
3. What are the DORA metrics?
   Four key metrics for measuring DevOps performance: deployment frequency, lead time for changes, change failure rate, and mean time to recovery (MTTR).
4. What is the difference between DevOps and SRE?
   DevOps is a broad culture/methodology; SRE is a specific implementation pioneered by Google that applies software engineering to operations using SLOs, error budgets, and toil reduction.
5. What is “shift left”?
   Moving activities like testing and security earlier in the development lifecycle to catch issues sooner and cheaper.
6. Name popular DevOps tools and their categories.
   Git (version control), GitHub Actions/Jenkins/GitLab CI (CI/CD), Docker (containers), Kubernetes (orchestration), Terraform/Ansible (IaC/config), Prometheus/Grafana (monitoring), Argo CD (GitOps).

Version Control & Git

7. What is the difference between Git merge and rebase?
   Merge creates a new commit joining two branches and preserves history; rebase replays commits onto a new base for a linear history but rewrites commit hashes.
8. What is a Git pull request?
   A request to merge changes from one branch into another, enabling code review, automated checks, and discussion before integration.
9. What is trunk-based development?
   A branching model where developers commit small changes frequently to a single main branch, relying on feature flags and CI to keep it releasable.
10. How do you revert a commit that has already been pushed?
    Use git revert <commit> to create a new commit that undoes the change, preserving history (safer than reset on shared branches).

CI/CD

11. What is Continuous Integration (CI)?
    The practice of frequently merging code changes into a shared repository, where each change is automatically built and tested.
12. What is the difference between Continuous Delivery and Continuous Deployment?
    Continuous Delivery automates everything up to a manual approval before production; Continuous Deployment automatically releases every passing change to production.
13. What is a CI/CD pipeline?
    An automated sequence of stages — build, test, scan, and deploy — that takes code from commit to production.
14. What is GitHub Actions?
    GitHub’s native CI/CD platform that runs workflows defined in YAML, triggered by events like push or pull request. It’s the most widely adopted CI/CD tool in 2026.
15. What are common deployment strategies?
    Rolling, blue-green, canary, and feature-flag-based deployments — each balancing risk, speed, and rollback ability.
16. What is an artifact in CI/CD?
    A build output (e.g., a JAR, container image, or binary) stored in a registry/repository and promoted through environments.

Containers & Docker

17. What is the difference between a container and a virtual machine?
    Containers share the host OS kernel and are lightweight; VMs run a full guest OS and are heavier and slower to start.
18. What is the difference between an image and a container?
    An image is a read-only template; a container is a running instance of that image.
19. What is a multi-stage Docker build?
    A Dockerfile technique that uses multiple FROM stages to keep build tooling out of the final image, producing smaller, more secure images.
20. How do you reduce Docker image size?
    Use minimal base images (Alpine/distroless), multi-stage builds, combine RUN layers, and add a .dockerignore.
21. What is the difference between CMD and ENTRYPOINT?
    ENTRYPOINT sets the fixed executable; CMD provides default arguments that can be overridden at runtime.
22. How do you persist data in Docker?
    Use volumes (managed by Docker) or bind mounts (host paths) so data survives container restarts and removal.

Kubernetes

23. What is Kubernetes?
    An open-source container orchestration platform that automates deployment, scaling, self-healing, and management of containerized applications.
24. What is a Pod?
    The smallest deployable unit in Kubernetes — one or more containers sharing network and storage.
25. What is the difference between a Deployment and a StatefulSet?
    Deployments manage stateless, interchangeable Pods; StatefulSets manage stateful Pods with stable identities and ordered, persistent storage.
26. What is a Service in Kubernetes?
    A stable network endpoint (ClusterIP, NodePort, or LoadBalancer) that exposes a set of Pods.
27. What is an Ingress?
    An API object that manages external HTTP/HTTPS access to services, providing routing, TLS termination, and host/path-based rules.
28. What is the difference between ConfigMap and Secret?
    Both store configuration; Secrets are intended for sensitive data and are base64-encoded (and can be encrypted at rest), while ConfigMaps hold non-sensitive config.
29. What is Helm?
    A package manager for Kubernetes that bundles manifests into reusable, versioned “charts” with templated values.
30. How does Kubernetes perform self-healing?
    It restarts failed containers, reschedules Pods from dead nodes, and replaces Pods that fail liveness/readiness probes to match the desired state.
31. What is the difference between liveness and readiness probes?
    A liveness probe restarts an unhealthy container; a readiness probe controls whether a Pod receives traffic.

Infrastructure as Code & Configuration Management

32. What is Infrastructure as Code (IaC)?
    Managing and provisioning infrastructure through machine-readable definition files rather than manual processes.
33. What is the difference between Terraform and Ansible?
    Terraform is primarily a declarative provisioning/IaC tool; Ansible is primarily a procedural configuration-management tool. They are often used together.
34. What is the Terraform state file and why does it matter?
    It maps your configuration to real resources. It must be stored in a remote, locked backend for team use to prevent corruption and conflicts.
35. What is the difference between declarative and imperative IaC?
    Declarative describes the desired end state (Terraform); imperative describes the steps to reach it (shell scripts).
36. What is idempotency?
    An operation that produces the same result no matter how many times it runs — a core property of good IaC and config management.
37. What is OpenTofu?
    An open-source, community-driven fork of Terraform under the Linux Foundation, providing a drop-in alternative after Terraform’s license change.

Monitoring, Observability & SRE

38. What are the three pillars of observability?
    Metrics, logs, and traces.
39. What is Prometheus?
    An open-source monitoring system that scrapes and stores time-series metrics and supports alerting via PromQL.
40. What is the difference between monitoring and observability?
    Monitoring tells you whether a system is working (known failure modes); observability lets you explore why it isn’t (unknown failure modes).
41. What are SLI, SLO, and SLA?
    SLI is a measured indicator (e.g., latency); SLO is the target for that indicator; SLA is the contractual agreement with consequences.
42. What is an error budget?
    The allowable amount of unreliability (1 − SLO). When exhausted, teams prioritize reliability over new features.
43. What is OpenTelemetry?
    A vendor-neutral standard and toolkit for generating and collecting metrics, logs, and traces — the de facto observability standard in 2026.

GitOps, Security & Modern Practices

44. What is GitOps?
    An operational model where Git is the single source of truth for declarative infrastructure and apps, and tools like Argo CD or Flux continuously reconcile the cluster to match Git.
45. What is DevSecOps?
    Integrating security into every stage of the DevOps pipeline — code scanning, image scanning, IaC scanning, and policy as code.
46. How do you manage secrets in a pipeline?
    Use a secrets manager (Vault, AWS/Azure/GCP secret managers), inject at runtime, never commit secrets to Git, and rotate regularly.
47. What is a software supply chain attack, and how do you defend against it?
    An attack that compromises dependencies or build systems. Defenses include SBOMs, image signing (Cosign), pinned dependencies, and provenance attestation (SLSA).
48. What is Platform Engineering?
    Building an internal developer platform (IDP) with self-service “golden paths” so developers can ship safely without deep infrastructure knowledge.
49. What is AIOps?
    Applying AI/ML to operations — anomaly detection, automated incident triage, predictive scaling, and reducing alert fatigue. A major 2026 trend.
50. How would you debug a slow or failing deployment in production?
    Check recent changes and rollback options, inspect pipeline/logs, verify health checks and resource limits, review metrics and traces, isolate the failing component, and communicate via the incident process — then write a blameless postmortem.

Conclusion

These 50 questions cover the breadth of what DevOps interviews ask in 2026 — from fundamentals to GitOps, security, and AIOps. Pair this with hands-on practice and role-specific prep. For deeper dives, see our Docker, Kubernetes, and Terraform interview question guides, and map your skills with The Ultimate DevOps & SRE Roadmap.