2026 INTERVIEW BIBLE

# Top 50 DevOps Interview Questions & Answers 2026: The Ultimate Guide

"In 2026, Bangalore's top product firms have moved beyond 'What is a Pod?' to 'How do you troubleshoot a CrashLoopBackOff in a production cluster?' This guide prepares you for the high-pressure scenarios you will actually face."

## Phase 1: Containerization (Docker)

#### 1. How do you reduce the size of a Docker image in a production environment?

Answer: Use **Multi-stage builds** to separate the build environment from the runtime environment. Additionally, use lightweight base images like **Alpine Linux**, minimize the number of layers by combining `RUN` commands, and use `.dockerignore` to exclude unnecessary files.

#### 5. What is the difference between a Docker ENTRYPOINT and CMD?

Answer: `ENTRYPOINT` defines the main command of the image that cannot be easily overridden, while `CMD` provides default arguments for that command which can be overridden by the user during `docker run`.

## Phase 2: Orchestration (Kubernetes)

#### 15. Explain the Kubernetes 'Control Plane' components.

Answer: The Control Plane manages the cluster state. Key components include:

- kube-apiserver: The entry point for all REST commands.
- etcd: Consistent and highly-available key-value store for cluster data.
- kube-scheduler: Watches for new pods and assigns them to nodes.
- kube-controller-manager: Runs controller processes like node and replication controllers.

#### 22. How does a Service locate its Pods in K8s?

Answer: Through Labels and Selectors. The Service definition includes a selector that matches the labels assigned to the Pods it needs to target.

## Phase 3: Automation (CI/CD & IaC)

#### 35. What is 'Blue-Green' deployment vs 'Canary' deployment?

Answer: **Blue-Green** involves having two identical production environments; you switch all traffic from old (Blue) to new (Green) at once. **Canary** involves rolling out the new version to a small subset of users first before scaling to the entire infrastructure.

#### 42. How do you handle secrets in Terraform?

Answer: Never hardcode secrets. Use environment variables (prefixed with `TF_VAR_`), encrypted `.tfvars` files, or integrate with an external secret manager like **HashiCorp Vault** or **AWS Secrets Manager**.

### Practice Makes Perfect

Knowing the answers is half the battle. To master the tools required to answer these questions confidently in a practical round, visit our:

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