# Performance Optimization (DevOps) > Load testing, profiling, caching strategies, CDN, database optimization, autoscaling, troubleshooting performance issues - 22 interview questions - Senior - [Interview Questions: DevOps](https://sharpskill.dev/en/technologies/devops/interview-questions.md) ## 1. What is a CDN and what is its main advantage? **Answer** A CDN (Content Delivery Network) distributes static assets (images, CSS, JS) across servers geographically close to users. This reduces latency (typically from 500ms to 50ms) and offloads the main server. CloudFront (AWS), Cloudflare, and Fastly are common examples used to improve overall web application performance. ## 2. What is the main difference between load testing and stress testing? **Answer** Load testing evaluates performance under normal or expected load to verify the system meets SLAs (response time, throughput). Stress testing pushes the system beyond its limits to identify the breaking point and observe behavior under extreme conditions. Stress testing also reveals how the system recovers after overload. ## 3. Which metric is most important for measuring perceived user performance during a load test? **Answer** Latency at the 95th or 99th percentile (P95/P99) reflects the experience of the most impacted users, unlike average latency which masks spikes. A P99 of 2 seconds means 99% of requests are faster, but 1% experience slowdowns. Monitoring high percentiles helps identify performance issues before they affect a significant portion of users. ## 19 more questions available - Which profiling tool visualizes function calls and their execution time as a horizontal graph? - What does the acronym RED mean in the context of service monitoring? Sign up for free: https://sharpskill.dev/en/login ## Other DevOps interview topics - [Version Control & Git](https://sharpskill.dev/en/technologies/devops/interview-questions/version-control-git.md): 20 questions, Junior - [Linux Fundamentals](https://sharpskill.dev/en/technologies/devops/interview-questions/linux-fundamentals.md): 22 questions, Junior - [Shell Scripting & Bash](https://sharpskill.dev/en/technologies/devops/interview-questions/shell-scripting-bash.md): 20 questions, Mid-Level - [Networking Basics](https://sharpskill.dev/en/technologies/devops/interview-questions/networking-basics.md): 22 questions, Junior - [Docker Fundamentals](https://sharpskill.dev/en/technologies/devops/interview-questions/docker-fundamentals.md): 24 questions, Junior - [CI/CD Fundamentals](https://sharpskill.dev/en/technologies/devops/interview-questions/ci-cd-fundamentals.md): 18 questions, Junior - [GitHub Actions](https://sharpskill.dev/en/technologies/devops/interview-questions/github-actions.md): 22 questions, Mid-Level - [GitLab CI/CD](https://sharpskill.dev/en/technologies/devops/interview-questions/gitlab-ci.md): 22 questions, Mid-Level - [Jenkins](https://sharpskill.dev/en/technologies/devops/interview-questions/jenkins.md): 22 questions, Mid-Level - [Kubernetes Basics](https://sharpskill.dev/en/technologies/devops/interview-questions/kubernetes-basics.md): 26 questions, Mid-Level - [Kubernetes Networking](https://sharpskill.dev/en/technologies/devops/interview-questions/kubernetes-networking.md): 24 questions, Mid-Level - [Kubernetes Advanced](https://sharpskill.dev/en/technologies/devops/interview-questions/kubernetes-advanced.md): 24 questions, Mid-Level - [Ingress & API Gateway](https://sharpskill.dev/en/technologies/devops/interview-questions/ingress-api-gateway.md): 20 questions, Mid-Level - [Terraform Basics](https://sharpskill.dev/en/technologies/devops/interview-questions/terraform-basics.md): 22 questions, Mid-Level - [Terraform Advanced](https://sharpskill.dev/en/technologies/devops/interview-questions/terraform-advanced.md): 22 questions, Mid-Level - [Ansible & Configuration Management](https://sharpskill.dev/en/technologies/devops/interview-questions/ansible-configuration.md): 20 questions, Mid-Level - [AWS Essentials](https://sharpskill.dev/en/technologies/devops/interview-questions/aws-essentials.md): 26 questions, Mid-Level - [Azure Fundamentals](https://sharpskill.dev/en/technologies/devops/interview-questions/azure-fundamentals.md): 22 questions, Mid-Level - [GCP Fundamentals](https://sharpskill.dev/en/technologies/devops/interview-questions/gcp-fundamentals.md): 22 questions, Mid-Level - [Monitoring & Prometheus](https://sharpskill.dev/en/technologies/devops/interview-questions/monitoring-prometheus.md): 22 questions, Mid-Level - [Logging & ELK Stack](https://sharpskill.dev/en/technologies/devops/interview-questions/logging-elk.md): 20 questions, Mid-Level - [Alerting & Incident Response](https://sharpskill.dev/en/technologies/devops/interview-questions/alerting-incident-response.md): 20 questions, Mid-Level - [Cloud Identity & Secrets](https://sharpskill.dev/en/technologies/devops/interview-questions/cloud-identity-secrets.md): 22 questions, Mid-Level - [CI/CD Pipeline Security](https://sharpskill.dev/en/technologies/devops/interview-questions/cicd-pipeline-security.md): 20 questions, Mid-Level - [Helm & Kubernetes](https://sharpskill.dev/en/technologies/devops/interview-questions/helm-kubernetes.md): 20 questions, Mid-Level - [Runtime & Cluster Security](https://sharpskill.dev/en/technologies/devops/interview-questions/runtime-cluster-security.md): 24 questions, Senior - [Container Supply Chain Security](https://sharpskill.dev/en/technologies/devops/interview-questions/container-supply-chain.md): 22 questions, Senior - [Service Mesh & Istio](https://sharpskill.dev/en/technologies/devops/interview-questions/service-mesh-istio.md): 24 questions, Senior - [GitOps & ArgoCD](https://sharpskill.dev/en/technologies/devops/interview-questions/gitops-argocd.md): 22 questions, Senior - [Progressive Delivery](https://sharpskill.dev/en/technologies/devops/interview-questions/progressive-delivery.md): 20 questions, Senior - [Distributed Observability](https://sharpskill.dev/en/technologies/devops/interview-questions/observability-distributed.md): 22 questions, Senior - [Disaster Recovery & Backup](https://sharpskill.dev/en/technologies/devops/interview-questions/disaster-recovery.md): 20 questions, Senior - [Cloud Cost Optimization](https://sharpskill.dev/en/technologies/devops/interview-questions/infrastructure-cost.md): 20 questions, Senior - [SRE Principles](https://sharpskill.dev/en/technologies/devops/interview-questions/sre-principles.md): 24 questions, Senior - [Chaos Engineering](https://sharpskill.dev/en/technologies/devops/interview-questions/chaos-engineering.md): 20 questions, Senior - [Platform Engineering](https://sharpskill.dev/en/technologies/devops/interview-questions/platform-engineering.md): 22 questions, Senior --- Source: SharpSkill (https://sharpskill.dev), tech interview preparation for your real stack. 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