AWS Interview Questions and Answers

1. What are the core AWS services?

   • Answer: Core AWS services include Compute (EC2), Storage (S3, EBS, Glacier), Database (RDS, DynamoDB, Redshift), Networking (VPC, Route 53), and Management Tools (CloudWatch, CloudTrail).

2. Explain the difference between EC2 and Lambda.

   • Answer: EC2 provides virtual servers you manage, while Lambda is a serverless compute service where AWS manages the infrastructure. Use EC2 for applications needing persistent resources or complex control, and Lambda for event-driven functions or microservices.

3. What are Amazon S3 storage classes?

   • Answer: S3 offers various storage classes optimized for different access patterns and costs: Standard, Intelligent-Tiering, Standard-IA, One Zone-IA, Glacier Instant Retrieval, Glacier Flexible Retrieval, Glacier Deep Archive. Choosing the right class balances cost and access speed.

4. Describe Amazon RDS.

   • Answer: Amazon RDS is a managed relational database service. It simplifies setting up, operating, and scaling relational databases like MySQL, PostgreSQL, Oracle, and SQL Server in the cloud. AWS handles patching, backups, and maintenance.

5. What is Amazon DynamoDB?

   • Answer: DynamoDB is a fully managed, serverless NoSQL database service. It's a key-value and document database offering high performance and scalability for applications requiring fast access to large datasets.

6. Explain Amazon VPC.

   • Answer: Amazon VPC lets you create a logically isolated section of the AWS Cloud dedicated to your resources. It provides you with control over your virtual network's configuration, including IP address ranges, subnets, and security groups.

7. What is AWS Elastic Beanstalk?

   • Answer: Elastic Beanstalk is a service that simplifies deploying and managing web applications and services on AWS. It handles capacity provisioning, load balancing, scaling, and application health monitoring.

8. What are AWS IAM roles?

   • Answer: IAM roles are virtual security credentials that grant access to AWS resources without requiring usernames and passwords. They are used to grant temporary access to EC2 instances and other services.

9. Explain the difference between an IAM user and an IAM role.

   • Answer: IAM users are long-lived identities associated with a person or application, requiring credentials like passwords. IAM roles are temporary security credentials assigned to AWS resources (e.g., EC2 instances), eliminating the need for long-term credentials.

10. What is AWS CloudFormation?

    • Answer: CloudFormation is a service for provisioning and managing AWS resources in a declarative manner. You define infrastructure as code (IaC) using JSON or YAML templates, and CloudFormation handles creating and updating the resources.

11. What is AWS CloudWatch?

    • Answer: CloudWatch is a monitoring and logging service for AWS resources and applications. It collects metrics, logs, and events to help you monitor the performance and health of your systems.

12. What is AWS CloudTrail?

    • Answer: CloudTrail provides a record of API calls made to your AWS account. This audit trail helps with security analysis, troubleshooting, and compliance auditing.

13. What is AWS SQS?

    • Answer: SQS (Simple Queue Service) is a message queuing service that helps decouple microservices and distribute tasks asynchronously. It helps improve application scalability and reliability.

14. What is AWS SNS?

    • Answer: SNS (Simple Notification Service) is a pub/sub messaging service used for fan-out messaging. It allows you to send messages to multiple subscribers, such as email, SMS, SQS, or other applications.

15. What is AWS KMS?

    • Answer: KMS (Key Management Service) manages encryption keys used to protect data both at rest and in transit. It provides secure key generation, storage, and rotation.

16. Explain AWS Auto Scaling.

    • Answer: Auto Scaling automatically adjusts the number of EC2 instances in response to demand. It ensures your applications have sufficient capacity to handle traffic spikes and remain available.

17. What is an AWS Elastic Load Balancer (ELB)?

    • Answer: ELB distributes incoming application traffic across multiple EC2 instances, ensuring high availability and preventing overload of individual servers.

18. What is AWS Route 53?

    • Answer: Route 53 is a highly available and scalable Domain Name System (DNS) web service. It routes users to your applications and content using domain names.

19. What are AWS security groups?

    • Answer: Security groups act as virtual firewalls for EC2 instances, controlling inbound and outbound traffic based on rules you define.

20. What are AWS NACLs (Network ACLs)?

    • Answer: Network ACLs provide an additional layer of security for subnets within a VPC. They filter traffic at the subnet level, offering more granular control than security groups.

21. Explain the difference between Security Groups and NACLs.

    • Answer: Security groups control traffic to and from EC2 instances, while NACLs control traffic at the subnet level. Security groups are stateful, while NACLs are stateless. Security groups are instance-level, and NACLs are subnet-level.

22. What is AWS Direct Connect?

    • Answer: Direct Connect establishes a dedicated network connection between your on-premises network and AWS, providing higher bandwidth and lower latency than using the public internet.

23. What is AWS CloudFront?

    • Answer: CloudFront is a Content Delivery Network (CDN) that caches your content closer to users, improving performance and reducing latency.

24. What is AWS Redshift?

    • Answer: Redshift is a fully managed, petabyte-scale data warehouse service in the cloud. It provides fast query performance for large datasets using columnar storage.

25. What is AWS EMR?

    • Answer: EMR (Elastic MapReduce) is a managed Hadoop framework service. It simplifies running big data processing jobs on AWS using tools like Spark and Hive.

26. What is AWS Glue?

    • Answer: Glue is a serverless ETL (Extract, Transform, Load) service that simplifies data integration and preparation for analytics.

27. What is AWS Athena?

    • Answer: Athena is an interactive query service that lets you analyze data directly in S3 using standard SQL. No infrastructure management is required.

28. What is AWS QuickSight?

    • Answer: QuickSight is a business intelligence (BI) service that lets you create visualizations and dashboards from your data.

29. What are AWS Lambda layers?

    • Answer: Lambda layers are packages of code, data, or configuration that can be reused across multiple Lambda functions. This promotes code modularity and reusability.

30. What is AWS X-Ray?

    • Answer: X-Ray helps debug and analyze distributed applications. It provides insights into the performance and behavior of microservices.

31. What is AWS Organizations?

    • Answer: Organizations is a service for managing multiple AWS accounts centrally. It allows for consolidated billing, policy management, and governance across different accounts.

32. What is AWS WAF (Web Application Firewall)?

    • Answer: WAF protects web applications from common web exploits like SQL injection and cross-site scripting (XSS).

33. What is AWS Shield?

    • Answer: Shield protects against DDoS (Distributed Denial of Service) attacks.

34. What is AWS Inspector?

    • Answer: Inspector automatically assesses the security configurations of your AWS resources, identifying potential vulnerabilities.

35. What is AWS Config?

    • Answer: Config provides an inventory of your AWS resources and tracks configuration changes, helping with compliance and auditing.

36. What is AWS Systems Manager?

    • Answer: Systems Manager provides tools for managing and automating tasks across your AWS infrastructure, including patch management and configuration management.

37. What is AWS OpsWorks?

    • Answer: OpsWorks provides tools for managing and automating chef and puppet configurations for EC2 instances.

38. Explain the difference between on-premises and cloud computing.

    • Answer: On-premises computing involves owning and managing your own hardware and infrastructure, while cloud computing involves using resources provided by a third-party provider like AWS.

39. What are the different AWS deployment models?

    • Answer: Different AWS deployment models include IaaS (Infrastructure as a Service), PaaS (Platform as a Service), and SaaS (Software as a Service).

40. What are the benefits of using AWS?

    • Answer: Benefits include scalability, cost-effectiveness, increased agility, high availability, global reach, and managed services.

41. How does AWS handle backups?

    • Answer: AWS offers various backup solutions, depending on the service. Many services offer automated backups, while others integrate with backup services like AWS Backup.

42. How does AWS handle security?

    • Answer: AWS employs a shared responsibility model where AWS is responsible for the security *of* the cloud, while customers are responsible for security *in* the cloud.

43. What is a high availability architecture?

    • Answer: A high availability architecture is designed to minimize downtime and ensure applications remain accessible even in case of failures.

44. What are some strategies for cost optimization on AWS?

    • Answer: Strategies include right-sizing instances, using spot instances, utilizing reserved instances, employing serverless technologies, and regularly monitoring and optimizing resource usage.

45. Explain the concept of serverless computing.

    • Answer: Serverless computing is an execution model where the cloud provider dynamically manages the allocation of compute resources. You only pay for the compute time consumed by your code.

46. What is a microservices architecture?

    • Answer: A microservices architecture involves structuring an application as a collection of small, independent services that communicate with each other.

47. What are some common AWS pricing models?

    • Answer: Common AWS pricing models include on-demand, reserved instances, spot instances, and pay-per-use.

48. Describe the process of deploying an application to AWS.

    • Answer: This depends on the application type and desired architecture. Options range from simple deployments to EC2 instances to using services like Elastic Beanstalk, Lambda, or container services like ECS or EKS.

49. How do you monitor the performance of your AWS resources?

    • Answer: Use CloudWatch to monitor metrics, logs, and events from your AWS resources. Set up alarms to be notified of potential issues.

50. How do you manage access to your AWS resources?

    • Answer: Use IAM to manage users, groups, and policies, controlling access to resources based on the principle of least privilege.

51. What are some best practices for securing your AWS environment?

    • Answer: Employ the principle of least privilege, regularly rotate credentials, use strong passwords and MFA, enable encryption, monitor logs and alerts, and regularly review security groups and NACLs.

52. How do you handle failures in an AWS environment?

    • Answer: Implement redundancy, use auto-scaling, leverage load balancers, and implement robust monitoring and alerting to quickly identify and recover from failures.

53. What is the AWS Well-Architected Framework?

    • Answer: The AWS Well-Architected Framework provides a set of best practices for designing and operating reliable, secure, efficient, cost-effective, and operable systems on AWS.

54. What is Amazon Machine Learning (Amazon ML)?

    • Answer: Amazon ML is a service that allows users to build machine learning models without needing extensive machine learning expertise. It’s been largely superseded by other more feature-rich services like SageMaker.

55. What is Amazon SageMaker?

    • Answer: SageMaker is a fully managed service for building, training, and deploying machine learning models at scale. It offers a comprehensive suite of tools for data preparation, model building, training, and deployment.

56. What is AWS Step Functions?

    • Answer: Step Functions is a service for coordinating multiple AWS services into complex workflows. It allows you to define and manage state machines to orchestrate tasks and processes.

57. What is AWS AppSync?

    • Answer: AppSync is a fully managed service that simplifies building scalable, real-time, and offline-capable applications using GraphQL.

58. What is AWS Amplify?

    • Answer: Amplify is a development platform for building full-stack applications powered by AWS. It offers a streamlined workflow for creating and deploying web, mobile, and IoT applications.

59. What is AWS IoT Core?

    • Answer: IoT Core is a managed cloud service that allows secure and scalable connection of IoT devices to the AWS cloud.

60. What is AWS Greengrass?

    • Answer: Greengrass extends AWS services to edge devices, enabling local processing and reduced latency for IoT applications.

61. What is AWS RoboMaker?

    • Answer: RoboMaker is a cloud robotics platform for developing, testing, and deploying robotic applications.

62. What is AWS Outposts?

    • Answer: Outposts extends AWS infrastructure and services to on-premises locations, allowing customers to run AWS services locally.

63. What is AWS Local Zones?

    • Answer: Local Zones provide AWS services closer to specific geographic locations, reducing latency for applications that require low latency access.

64. What is AWS Wavelength?

    • Answer: Wavelength brings AWS compute and services closer to mobile networks, enabling low-latency applications at the edge.

65. What is Amazon Lightsail?

    • Answer: Lightsail is a simplified service for deploying and managing virtual servers, databases, and other resources, ideal for beginners and small-scale applications.

66. What are the different types of Amazon EC2 instances?

    • Answer: EC2 offers a wide variety of instance types optimized for different workloads, including general purpose, compute optimized, memory optimized, storage optimized, accelerated computing, and more.

67. What is the difference between Amazon EC2 instance types?

    • Answer: Different instance types offer different combinations of CPU, memory, storage, and networking capabilities to suit various application needs.

68. What are Elastic IP addresses in AWS?

    • Answer: Elastic IPs are static public IP addresses that you can associate with your EC2 instances. This ensures a consistent IP address even if the underlying instance changes.

69. What is Amazon EBS (Elastic Block Store)?

    • Answer: EBS provides block storage volumes that you can attach to your EC2 instances. They are persistent and offer various performance levels.

70. What are the different types of Amazon EBS volumes?

    • Answer: Different EBS volume types offer different performance characteristics, including general purpose SSD (gp3), provisioned IOPS SSD (io2), throughput optimized HDD (st1), cold HDD (sc1), and others, allowing optimization for diverse workloads.

71. What is Amazon EFS (Elastic File System)?

    • Answer: EFS provides a fully managed file system that can be accessed by multiple EC2 instances. It scales automatically to handle growing data requirements.

72. What is Amazon FSx?

    • Answer: FSx offers fully managed file systems optimized for different workloads, including Windows File Server, NetApp ONTAP, and Lustre for high-performance computing.

73. What are AWS Elastic Load Balancing (ELB) target groups?

    • Answer: Target groups define the set of EC2 instances or other targets that receive traffic from an Elastic Load Balancer.

74. Explain the different types of AWS Elastic Load Balancing (ELB).

    • Answer: Different ELB types include Application Load Balancers (ALB), Network Load Balancers (NLB), and Classic Load Balancers (now largely deprecated). Each offers different features and capabilities for various use cases.

75. What is AWS Certificate Manager (ACM)?

    • Answer: ACM provides a free and easy way to provision, manage, and deploy SSL/TLS certificates for your AWS services, simplifying secure communications.

76. What is AWS Cloud9?

    • Answer: Cloud9 is a cloud-based integrated development environment (IDE) that lets you write, run, and debug code in your browser.

77. What is AWS CodePipeline?

    • Answer: CodePipeline is a continuous delivery service that automates the build, test, and release process for your software applications.

78. What is AWS CodeDeploy?

    • Answer: CodeDeploy automates the deployment of your application code to AWS or on-premises instances.

79. What is AWS CodeBuild?

    • Answer: CodeBuild is a fully managed continuous integration service that compiles source code, runs tests, and produces software packages.

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