# AWS Essentials (DevOps) > EC2, S3, VPC, IAM, RDS, Lambda, CloudWatch, ELB, Auto Scaling, troubleshooting AWS service issues - 26 interview questions - Mid-Level - [Interview Questions: DevOps](https://sharpskill.dev/en/technologies/devops/interview-questions.md) ## 1. What is an EC2 instance in AWS? **Answer** EC2 (Elastic Compute Cloud) is AWS's virtual server service, allowing users to rent computing capacity in the cloud. Unlike physical servers, EC2 instances launch in minutes and are billed by usage. EC2 is suitable for hosting web applications, databases, or any workload requiring full operating system control. ## 2. What is the primary role of the S3 service? **Answer** S3 (Simple Storage Service) is AWS's object storage service, designed to store and retrieve unlimited amounts of data. Each object is identified by a unique key within a bucket. S3 is ideal for backups, static website hosting, data lakes, and media asset storage thanks to its 99.999999999% durability and various storage classes. ## 3. What does a Security Group allow you to configure in AWS? **Answer** A Security Group acts as a virtual firewall at the EC2 instance level, controlling inbound and outbound traffic through stateful rules. Rules allow connections by protocol, port, and source IP or CIDR. Security Groups are associated with instances and evaluate traffic before it reaches the instance, forming the first line of network defense. ## 23 more questions available - What is a VPC in AWS? - Which AWS service should be used to run code without managing servers? 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 - [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 - [Performance Optimization](https://sharpskill.dev/en/technologies/devops/interview-questions/performance-optimization.md): 22 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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