Top 60 DevOps Most Asked Interview Questions

DevOps is a cultural and technical practice that integrates software development (Dev) and IT operations (Ops) to shorten the development lifecycle and deliver high-quality software continuously.

Key Benefits:

1. Faster software delivery
2. Improved collaboration between teams
3. Continuous integration & deployment (CI/CD)
4. Early bug detection
5. Increased reliability and scalability

The main phases of the DevOps lifecycle are:

1. Planning
2. Coding
3. Building
4. Testing
5. Releasing
6. Deploying
7. Operating
8. Monitoring

CI (Continuous Integration):

1. Merging code changes frequently and testing automatically

CD (Continuous Delivery/Deployment):

1. Automating the release and deployment of applications to production

Version control tracks code changes, allowing multiple developers to collaborate safely.

Example tools: Git, GitHub, GitLab, Bitbucket

Popular DevOps Tools:

1. CI/CD: Jenkins, GitLab CI, CircleCI
2. Configuration Management: Ansible, Puppet, Chef
3. Containerization: Docker, Podman
4. Orchestration: Kubernetes
5. Monitoring: Prometheus, Grafana, ELK Stack

Infrastructure as Code (IaC) is managing infrastructure (servers, networks, etc.) using code instead of manual setup.

Tools: Terraform, AWS CloudFormation, Ansible

Agile:

1. Focuses on iterative software development

DevOps:

1. Focuses on automating deployment, operations, and collaboration between Dev and Ops teams

Containerization packages applications with all dependencies, ensuring consistent environments across systems.

Docker simplifies creation, deployment, and management of containers.

Kubernetes (K8s) is a container orchestration platform used to automate deployment, scaling, and management of containerized applications.

A Jenkins pipeline automates build, test, and deployment processes using a scripted or declarative syntax in Jenkinsfiles.

Security Practices in DevOps:

1. Use DevSecOps practices
2. Regular code scans (SonarQube, Snyk)
3. Secrets management (Vault, AWS Secrets Manager)
4. Role-based access and audit logging

Continuous Monitoring is monitoring application and infrastructure performance in real-time to detect and fix issues quickly.

Tools: Prometheus, Grafana, ELK Stack, Datadog

Continuous Delivery:

1. Code is ready for deployment but requires manual approval

Continuous Deployment:

1. Code is automatically deployed to production without manual steps

Configuration management ensures consistency across environments by automating setup and maintenance of servers using tools like Ansible, Puppet, or Chef.

Blue-Green Deployment involves maintaining two identical environments — Blue (current) and Green (new).

Traffic is switched to Green after successful testing, minimizing downtime.

A microservices architecture is an architectural style where an application is built as a collection of loosely coupled, independently deployable services.

Artifacts are compiled versions of code (e.g., JAR, WAR, Docker image).

Tools: Nexus, Artifactory, AWS CodeArtifact

Rollback means reverting to the previous stable version during a failed deployment using versioned builds, Kubernetes rollbacks, or CI/CD scripts.

Common Challenges:

1. Resistance to cultural change
2. Toolchain complexity
3. Security integration (DevSecOps)
4. Legacy system compatibility
5. Lack of automation and skills

Branching strategies define how teams manage features, releases, and fixes.

Common ones:

1. Git Flow: feature, develop, release, hotfix branches
2. GitHub Flow: main + feature branches
3. Trunk-based development: single main branch, small frequent commits

Merge:

1. Combines branches and preserves commit history

Rebase:

1. Moves commits on top of another branch for a cleaner linear history

A reverse proxy routes client requests to backend servers and provides load balancing, caching, SSL termination, and security.

Example: Nginx, HAProxy

Master Node:

1. API Server, etcd, Scheduler, Controller Manager

Worker Node:

1. Kubelet, Kube Proxy, Container Runtime

Helm is a Kubernetes package manager. A Helm chart defines a set of Kubernetes resources for deploying applications easily.

Terraform:

1. Infrastructure provisioning (declarative)

Ansible:

1. Configuration management & automation (procedural)
2. Terraform is often used before Ansible in a pipeline

Immutable servers are never modified after deployment. Instead of updating, a new server instance is created with the required changes.

Include unit tests, integration tests, and end-to-end tests using frameworks like JUnit, PyTest, Selenium, etc., triggered automatically in Jenkins or GitHub Actions.

A load balancer distributes incoming network traffic across multiple servers to improve availability and performance.

Examples: Nginx, AWS ELB, HAProxy

Shifting left means performing testing, security checks, and validation earlier in the development cycle to detect issues sooner.

A canary deployment is a deployment strategy where a small subset of users gets the new version first. If stable, it gradually rolls out to everyone.

Monolithic:

1. Single codebase, hard to scale

Microservices:

1. Multiple independent services, easier scaling, better fault isolation

Store API keys, passwords, and tokens securely using:

1. HashiCorp Vault
2. AWS Secrets Manager
3. Kubernetes Secrets
4. GitHub Encrypted Secrets

Observability = Monitoring + Logging + Tracing

It helps understand the internal state of systems using data such as logs, metrics, and traces.

Key Performance Indicators:

1. Deployment frequency
2. Lead time for changes
3. Mean time to recovery (MTTR)
4. Change failure rate

They store dynamic configuration data like API keys, ports, or database URLs — separate from code for portability and security.

Virtualization:

1. Uses hypervisors (VMware, VirtualBox) to run multiple OS instances

Containerization:

1. Shares the host OS kernel but isolates apps (Docker)

Logs track events and errors in applications. They are crucial for debugging, auditing, and performance optimization.

Tools: ELK Stack, Fluentd, Loki

A service mesh manages secure communication between microservices.

Examples: Istio, Linkerd

It handles traffic routing, retries, encryption, and monitoring.

A rolling deployment is a strategy where updates are deployed gradually to instances one at a time, ensuring zero downtime.

Docker Compose:

1. Used for defining and running multi-container Docker applications on a single host

Kubernetes:

1. Orchestrates and manages containers across multiple nodes in a cluster, handling scaling, networking, and auto-healing

Security Practices:

1. Use least-privilege access controls
2. Scan dependencies (Snyk, Trivy)
3. Encrypt secrets & credentials
4. Enforce code signing and artifact validation
5. Implement automated security tests

Kubernetes automatically restarts the failed pod, reschedules it on another node if necessary, and maintains the desired state defined in the deployment.

Use Infrastructure as Code tools like Terraform and Configuration Management tools like Ansible to enforce consistent configurations automatically.

A sidecar container is a secondary container that runs alongside the main application container to handle auxiliary tasks such as logging, monitoring, or proxying (common in service meshes).

Blue-Green:

1. Two environments (old & new). Switch traffic completely after testing

Canary:

1. Gradually roll out to a small percentage of users and monitor before full rollout

Use:

This reverts the application to the previous stable version.

Vertical scaling:

1. Add more resources (CPU/RAM) to a single instance

Horizontal scaling:

1. Add more instances (pods, servers) to handle increased load

Zero-Downtime Deployment Strategies:

1. Use rolling or blue-green deployments
2. Load balancers to manage live traffic
3. Health checks and readiness probes
4. Use feature flags to toggle new features safely

Ingress manages external access to Kubernetes services, typically HTTP/HTTPS, allowing domain-based routing and SSL termination.

Terraform stores the infrastructure's state in a state file (terraform.tfstate) locally or remotely (e.g., AWS S3). This helps Terraform track changes and apply only the differences.

Terraform:

1. Open-source, multi-cloud tool by HashiCorp

CloudFormation:

1. AWS-native IaC tool for AWS resources only

An ephemeral environment is a short-lived, on-demand environment (like a temporary test or staging setup) that's automatically created during CI/CD and destroyed after use.

Use APM (Application Performance Monitoring) tools like:

1. New Relic
2. Datadog
3. Prometheus + Grafana
4. AWS CloudWatch

They track latency, CPU, memory, errors, and request rates.

High Availability Strategies:

1. Deploy applications across multiple zones/regions
2. Use load balancers and auto-scaling
3. Replicate databases
4. Implement health checks and failover strategies

Chaos engineering is a practice of intentionally introducing failures (e.g., shutting down instances) to test system resilience.

Tools: Chaos Monkey, LitmusChaos, Gremlin

Debugging Steps:

1. Check Jenkins console output logs
2. Validate Jenkinsfile syntax
3. Ensure plugins and environment variables are correct
4. Re-run with debug logs or safe mode to isolate issues

Environment Management:

1. Use environment-specific configuration files or variables
2. Use branches or separate pipelines for each environment
3. Deploy through promotion flow (dev → staging → prod)

They control which pods can be scheduled on which nodes.

Taint: Prevents pods from running on a node

Toleration: Allows specific pods to bypass the taint

Automated testing:

1. Uses scripts to run predefined tests

Continuous testing:

1. Integrates automated tests throughout the CI/CD pipeline for early and continuous feedback