DevOps Engineer Interview Questions

A complete guide covering Linux, Git, CI/CD, Docker, Kubernetes, Terraform, Ansible, AWS, Monitoring, and SRE concepts.

Total Questions:400
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1.What is the difference between soft link and hard link?

2.Explain the Linux boot process.

3.What are inodes in Linux?

4.How do you check disk usage in Linux?

5.What is the difference between /etc/passwd and /etc/shadow?

6.Explain file permissions in Linux (chmod, chown, chgrp).

7.What is umask?

8.How do you find files in Linux (find, locate, grep)?

9.What is the difference between kill and killall?

10.Explain different signals in Linux (SIGTERM, SIGKILL, SIGHUP).

11.What is a daemon process?

12.How do you check running processes (ps, top, htop)?

13.What is the difference between systemctl and service?

14.How do you troubleshoot high CPU usage?

15.How do you troubleshoot high memory usage?

16.What is swap space and when is it used?

17.How do you check network connections (netstat, ss, lsof)?

18.What is SELinux and AppArmor?

19.How do you manage services in Linux?

20.What is cron and how do you schedule jobs?

21.What is the difference between cron and anacron?

22.How do you check logs in Linux?

23.What is journalctl?

24.How do you compress and decompress files (tar, gzip, bzip2)?

25.What is the difference between /bin, /sbin, /usr/bin, /usr/sbin?

26.How do you mount and unmount filesystems?

27.What is LVM (Logical Volume Manager)?

28.How do you troubleshoot network issues?

29.What is SSH and how do you secure it?

30.How do you set up SSH key-based authentication?

31.What is shell scripting and why is it important in DevOps?

32.What is the difference between sh, bash, and zsh?

33.How do you make a script executable?

34.What is shebang (#!) in shell scripts?

35.Explain variables in shell scripting.

36.What is the difference between single quotes and double quotes?

37.How do you pass arguments to a shell script?

38.What are $0, $1, $#, $@, $*, $?

39.How do you use conditional statements (if-else)?

40.How do you use loops (for, while, until)?

41.What is the difference between [ ] and [[ ] ]?

42.How do you read user input in shell scripts?

43.What are functions in shell scripting?

44.How do you handle errors in shell scripts?

45.What is set -e, set -u, set -x?

46.How do you redirect output and errors?

47.What is the difference between > and >>?

48.What is piping and how does it work?

49.How do you use grep, sed, and awk?

50.What is the difference between grep, egrep, and fgrep?

51.How do you parse JSON in shell scripts (jq)?

52.How do you debug shell scripts?

53.What are exit codes and how do you use them?

54.How do you run commands in the background?

55.How do you schedule scripts using cron?

56.What is Git and why is it important in DevOps?

57.What is the difference between Git and GitHub?

58.Explain Git workflow.

59.What is the difference between git pull and git fetch?

60.What is git merge vs git rebase?

61.When would you use rebase over merge?

62.What is a merge conflict and how do you resolve it?

63.What is git cherry-pick?

64.What is git stash and when do you use it?

65.What is the difference between git reset and git revert?

66.Explain git reset --soft, --mixed, --hard.

67.What is a Git branch and branching strategy?

68.What is GitFlow workflow?

69.What is trunk-based development?

70.What is a pull request/merge request?

71.What are Git hooks?

72.How do you undo the last commit?

73.What is .gitignore?

74.How do you rename or delete a branch?

75.What is git bisect?

76.How do you find who changed a specific line of code (git blame)?

77.What is a detached HEAD state?

78.How do you squash commits?

79.What is git tag and when do you use it?

80.How do you resolve 'detached HEAD' situation?

81.What is CI/CD?

82.What is the difference between Continuous Integration, Continuous Delivery, and Continuous Deployment?

83.What CI/CD tools have you worked with?

84.Explain Jenkins architecture.

85.What is a Jenkins pipeline?

86.What is the difference between declarative and scripted pipeline?

87.What is Jenkinsfile?

88.How do you implement parallel execution in Jenkins?

89.What are Jenkins agents/slaves?

90.How do you secure Jenkins?

91.What is Jenkins Blue Ocean?

92.What is GitLab CI/CD?

93.What is .gitlab-ci.yml?

94.What are runners in GitLab?

95.What is GitHub Actions?

96.What is a workflow in GitHub Actions?

97.What is CircleCI?

98.What is Travis CI?

99.What is ArgoCD?

100.What is the difference between push-based and pull-based deployment?

101.How do you implement automated testing in CI/CD?

102.What is artifact management?

103.What is Nexus and Artifactory?

104.How do you implement security scanning in pipelines?

105.What is SAST and DAST?

106.What is dependency scanning?

107.How do you implement deployment strategies (blue-green, canary, rolling)?

108.What is pipeline as code?

109.How do you handle secrets in CI/CD pipelines?

110.What are best practices for CI/CD?

111.What is Docker and containerization?

112.What is the difference between containers and virtual machines?

113.What is a Docker image?

114.What is a Docker container?

115.What is Dockerfile?

116.Explain Dockerfile instructions (FROM, RUN, CMD, ENTRYPOINT, COPY, ADD).

117.What is the difference between CMD and ENTRYPOINT?

118.What is the difference between COPY and ADD?

119.What is Docker layering?

120.How do you optimize Docker images?

121.What is multi-stage build in Docker?

122.What is .dockerignore?

123.What is Docker Hub?

124.What is Docker registry?

125.What is the difference between public and private registry?

126.How do you run a Docker container?

127.What are Docker volumes?

128.What is the difference between bind mounts and volumes?

129.What is Docker networking?

130.Explain Docker network types (bridge, host, overlay, none).

131.How do containers communicate with each other?

132.What is Docker Compose?

133.What is docker-compose.yml?

134.How do you scale containers in Docker Compose?

135.What is the difference between docker run and docker start?

136.What is the difference between docker stop and docker kill?

137.How do you view container logs?

138.How do you access a running container?

139.What is docker exec vs docker attach?

140.How do you troubleshoot Docker containers?

141.What is Docker Swarm?

142.What is the difference between Docker Swarm and Kubernetes?

143.How do you secure Docker containers?

144.What is container runtime (containerd, CRI-O)?

145.What are Docker best practices?

146.What is Kubernetes?

147.What is the Kubernetes architecture?

148.What is a Kubernetes cluster?

149.What is the difference between master and worker nodes?

150.What are the components of master node (API server, scheduler, controller manager, etcd)?

151.What are the components of worker node (kubelet, kube-proxy, container runtime)?

152.What is etcd?

153.What is a Pod?

154.What is a ReplicaSet?

155.What is a Deployment?

156.What is the difference between ReplicaSet and Deployment?

157.What is a Service in Kubernetes?

158.Explain Service types (ClusterIP, NodePort, LoadBalancer, ExternalName).

159.What is a Namespace?

160.What is a ConfigMap?

161.What is a Secret?

162.What is the difference between ConfigMap and Secret?

163.What is a PersistentVolume (PV)?

164.What is a PersistentVolumeClaim (PVC)?

165.What is a StorageClass?

166.What is a StatefulSet?

167.What is the difference between Deployment and StatefulSet?

168.What is a DaemonSet?

169.What is a Job and CronJob?

170.What is an Ingress?

171.What is an Ingress Controller?

172.What is a NetworkPolicy?

173.What is RBAC in Kubernetes?

174.What is a ServiceAccount?

175.What is kubectl?

176.What are important kubectl commands?

177.What is a rolling update?

178.How do you rollback a deployment?

179.What is liveness probe and readiness probe?

180.What is the difference between liveness and readiness probes?

181.What is Horizontal Pod Autoscaler (HPA)?

182.What is Vertical Pod Autoscaler (VPA)?

183.What is resource requests and limits?

184.What is a Helm chart?

185.What is Helm and why use it?

186.What is Infrastructure as Code (IaC)?

187.What is Terraform?

188.What is the difference between Terraform and Ansible?

189.What is Terraform state file?

190.What is remote state in Terraform?

191.What is state locking?

192.What are Terraform providers?

193.What are Terraform resources?

194.What are Terraform modules?

195.What is the difference between resource and data source?

196.What is terraform init?

197.What is terraform plan?

198.What is terraform apply?

199.What is terraform destroy?

200.What is terraform validate?

201.What is terraform fmt?

202.What are Terraform variables?

203.What is the difference between variables and locals?

204.What are output values in Terraform?

205.What is terraform import?

206.What is terraform taint?

207.What are provisioners in Terraform?

208.What is the lifecycle block?

209.What is count vs for_each?

210.What are Terraform workspaces?

211.What is Ansible?

212.What is the difference between Ansible and Terraform?

213.What is an Ansible playbook?

214.What is an Ansible role?

215.What is inventory in Ansible?

216.What is the difference between static and dynamic inventory?

217.What are Ansible modules?

218.What is idempotency in Ansible?

219.What are handlers in Ansible?

220.What are facts in Ansible?

221.What is ansible-vault?

222.How do you manage secrets in Ansible?

223.What are variables in Ansible?

224.What is the precedence order of variables?

225.What are tags in Ansible?

226.What is the difference between include and import?

227.How do you test Ansible playbooks?

228.What is Ansible Galaxy?

229.What are best practices for Ansible?

230.How do you debug Ansible playbooks?

231.What AWS services are commonly used in DevOps?

232.What is EC2?

233.What is the difference between EC2 instance types?

234.What is Auto Scaling Group (ASG)?

235.What is Elastic Load Balancer (ELB)?

236.What is the difference between ALB, NLB, and CLB?

237.What is VPC (Virtual Private Cloud)?

238.What are subnets (public vs private)?

239.What is Internet Gateway and NAT Gateway?

240.What is Security Group vs NACL?

241.What is S3 and its use cases?

242.What are S3 storage classes?

243.What is CloudFront (CDN)?

244.What is Route 53?

245.What is RDS?

246.What is the difference between RDS and DynamoDB?

247.What is Lambda?

248.What is ECS vs EKS?

249.What is ECR?

250.What is CloudFormation?

251.What is observability?

252.What is the difference between monitoring and observability?

253.What is Prometheus?

254.What is Grafana?

255.How do you integrate Prometheus with Grafana?

256.What is the Prometheus architecture?

257.What is PromQL?

258.What is the Prometheus Alertmanager?

259.What is the ELK stack?

261.What is Logstash?

262.What is Kibana?

263.What is Filebeat?

264.What is the difference between Filebeat and Logstash?

265.What is the EFK stack (Elasticsearch, Fluentd, Kibana)?

266.What is Splunk?

267.What is Datadog?

268.What is New Relic?

269.What metrics do you monitor in production?

270.What is APM (Application Performance Monitoring)?

271.What is distributed tracing?

272.What is Jaeger?

273.What is the four golden signals of monitoring?

274.How do you set up alerts?

275.What is SLA, SLO, and SLI?

276.What is TCP/IP model?

277.What is OSI model?

278.What is the difference between TCP and UDP?

279.What is DNS and how does it work?

280.What is load balancing?

281.What are load balancing algorithms?

282.What is reverse proxy vs forward proxy?

283.What is NGINX?

284.What is the difference between NGINX and Apache?

285.What is SSL/TLS?

286.How does HTTPS work?

287.What is a firewall?

288.What is VPN?

289.What is port forwarding?

290.What is subnet mask and CIDR notation?

291.What is NAT (Network Address Translation)?

292.How do you troubleshoot network connectivity?

293.What is ping, traceroute, nslookup, dig?

294.What is the difference between stateful and stateless firewalls?

295.What is CDN (Content Delivery Network)?

296.What is DevSecOps?

297.How do you implement security in CI/CD?

298.What is vulnerability scanning?

299.What is SAST (Static Application Security Testing)?

300.What is DAST (Dynamic Application Security Testing)?

301.What is SCA (Software Composition Analysis)?

302.What is container scanning?

303.What is image signing?

304.What is secrets management?

305.What is HashiCorp Vault?

306.How do you rotate secrets?

307.What is the principle of least privilege (PoLP)?

308.What is zero trust security?

309.What is network segmentation?

310.What is encryption at rest vs in transit?

311.What is certificate management?

312.What is OAuth and JWT?

313.What is penetration testing?

314.What is compliance (SOC2, HIPAA, PCI-DSS)?

315.How do you handle security incidents?

316.What is security hardening?

317.What is patch management?

318.What is backup and disaster recovery (DR)?

319.What is RTO and RPO?

320.What are security best practices for cloud?

321.How do you troubleshoot application performance issues?

322.How do you debug a crashed container?

323.How do you troubleshoot pod failures in Kubernetes?

324.How do you investigate high latency?

325.How do you troubleshoot out of memory (OOM) errors?

326.How do you debug network connectivity issues?

327.How do you troubleshoot DNS resolution problems?

328.How do you investigate disk space issues?

329.How do you debug CI/CD pipeline failures?

330.How do you troubleshoot deployment failures?

331.How do you investigate security breaches?

332.How do you debug configuration issues?

333.How do you troubleshoot service discovery problems?

334.How do you investigate database connection issues?

335.How do you debug SSL/TLS certificate problems?

336.How do you troubleshoot load balancer issues?

337.How do you investigate API failures?

338.How do you debug intermittent issues?

339.What tools do you use for troubleshooting?

340.How do you perform root cause analysis (RCA)?

341.Design a CI/CD pipeline for a microservices application.

342.How would you implement zero-downtime deployment?

343.Design a monitoring and alerting system.

344.How would you migrate an application to Kubernetes?

345.Design a disaster recovery plan.

346.How would you implement auto-scaling for an application?

347.Design a multi-region deployment architecture.

348.How would you optimize infrastructure costs?

349.Design a secure DevOps pipeline.

350.How would you handle a production outage?

351.Design a backup and recovery strategy.

352.How would you implement blue-green deployment?

353.Design a logging and monitoring solution for microservices.

354.How would you containerize a legacy application?

355.Design a secrets management solution.

356.How would you implement canary deployment?

357.Design a multi-cloud strategy.

358.How would you improve application performance?

359.Design a GitOps workflow.

360.How would you implement infrastructure as code?

361.Tell me about the most challenging DevOps project you've worked on.

362.How do you handle production incidents?

363.Describe a time when you automated a manual process.

364.How do you stay updated with DevOps trends?

365.Tell me about a time you improved system reliability.

366.How do you handle disagreements with developers?

367.Describe your on-call experience.

368.How do you prioritize multiple urgent tasks?

369.Tell me about a time you made a critical mistake.

370.How do you handle stress during outages?

371.Describe your experience with agile methodology.

372.How do you communicate technical issues to non-technical stakeholders?

373.Tell me about a time you optimized costs.

374.How do you balance speed and stability?

375.Describe a time you implemented a new tool or technology.

376.What is GitOps?

377.What is ArgoCD and FluxCD?

378.What is service mesh (Istio, Linkerd)?

379.What is Envoy proxy?

380.What is chaos engineering?

381.What is immutable infrastructure?

382.What is serverless architecture?

383.What is FaaS (Function as a Service)?

384.What is edge computing?

385.What is container orchestration?

386.What is Nomad (HashiCorp)?

387.What is Consul?

388.What is OpenShift?

389.What is Rancher?

390.What is Platform Engineering?

391.What is internal developer platform (IDP)?

392.What is policy as code (OPA)?

393.What is FinOps?

394.What is SRE (Site Reliability Engineering)?

395.What is error budget?

396.What is toil in SRE?

397.What is trunk-based development?

398.What is feature toggles/flags?

399.What is infrastructure drift detection?

400.What is the future of DevOps?