AWS Interview Questions and Answers for 7 years experience

1. What are the different AWS global regions and why is regional selection important?

   • Answer: AWS has numerous global regions, each consisting of multiple Availability Zones. Regional selection is crucial for several reasons: data latency (choosing a region closer to your users reduces latency), data sovereignty (complying with data residency regulations), cost optimization (different regions have varying pricing), and disaster recovery (distributing resources across multiple regions for redundancy).

2. Explain the difference between EC2 instance types and how to choose the right one.

   • Answer: EC2 instance types are categorized by compute, memory, storage, and networking capabilities. Choosing the right one depends on your workload. Consider factors like CPU, memory requirements, storage needs (SSD vs. HDD), network performance (bandwidth, I/O), and cost. Use the EC2 instance type selection tools and consider whether you need optimized instances for specific tasks (e.g., compute-optimized, memory-optimized, GPU-optimized).

3. Describe different AWS storage services and their use cases.

   • Answer: AWS offers various storage services: S3 (object storage for unstructured data like images, videos, backups), EBS (block storage for EC2 instances), EFS (file storage for EC2 instances), Glacier (archival storage for long-term data retention), S3 Glacier Deep Archive (extremely low-cost archival), and others. The choice depends on the type of data, access frequency, cost requirements, and performance needs.

4. How do you ensure high availability and fault tolerance in an AWS environment?

   • Answer: High availability and fault tolerance are achieved through several strategies: using multiple Availability Zones, employing load balancing (ELB, ALB, NLB), implementing auto-scaling groups, using redundant databases (e.g., read replicas, multi-AZ deployments), and designing for failure by incorporating monitoring and alerting systems.

5. Explain the concept of AWS Lambda and its benefits.

   • Answer: AWS Lambda is a serverless compute service that runs code in response to events. Benefits include scalability (automatically scales based on demand), cost-effectiveness (pay only for compute time used), and reduced operational overhead (no server management required).

6. What are different AWS databases and when would you choose one over another?

   • Answer: AWS offers a wide range of database services, including RDS (managed relational databases like MySQL, PostgreSQL, Oracle), DynamoDB (NoSQL key-value and document database), Aurora (MySQL and PostgreSQL-compatible database), Redshift (data warehousing), and DocumentDB (MongoDB-compatible database). The choice depends on the type of data, scalability requirements, performance needs, and budget.

7. Describe the process of deploying an application to AWS using CI/CD.

   • Answer: A typical CI/CD pipeline on AWS might involve using services like CodeCommit (source control), CodeBuild (build automation), CodeDeploy (deployment automation), and CodePipeline (orchestrates the entire pipeline). The process involves continuous integration (building and testing code), continuous delivery (automating deployment to various environments), and potentially continuous deployment (automatic deployment to production).

8. Explain how AWS IAM works and its importance for security.

   • Answer: AWS Identity and Access Management (IAM) controls access to AWS resources. It uses identities (users, groups, roles) and policies (permissions) to define who can access what. It is crucial for security by implementing the principle of least privilege, granting only necessary permissions to users and services, and preventing unauthorized access.

9. How do you monitor and troubleshoot issues in your AWS environment?

   • Answer: AWS provides various monitoring and logging services: CloudWatch (metrics, logs, alarms), X-Ray (application tracing), CloudTrail (audit trail), and others. Troubleshooting involves using these services to identify performance bottlenecks, errors, and security issues. Log aggregation and analysis are crucial for effective troubleshooting.

10. What are AWS CloudFormation and AWS Elastic Beanstalk? When would you use each?

    • Answer: CloudFormation allows you to define and manage AWS resources using templates (JSON or YAML). It's ideal for infrastructure as code, automating deployments, and managing complex infrastructure. Elastic Beanstalk is a service for deploying and managing web applications and services. It simplifies deployment and handles scaling but offers less control over infrastructure compared to CloudFormation.

11. Explain the difference between VPC and subnet.

    • Answer: A VPC (Virtual Private Cloud) is a logically isolated section of the AWS Cloud, acting as your own private network. Subnets are divisions within a VPC, allowing for further isolation and control of resource placement. Subnets must be associated with an Availability Zone.

12. Describe different types of load balancing in AWS.

    • Answer: AWS offers Application Load Balancers (ALB), Classic Load Balancers (CLB), Network Load Balancers (NLB), and Gateway Load Balancers (GLB). ALBs operate at the application layer (HTTP/HTTPS), CLBs are legacy, NLBs operate at the transport layer (TCP/UDP), and GLBs route traffic to highly available targets in a VPC.

13. How do you handle security best practices in AWS?

    • Answer: Security best practices include using IAM for granular access control, enabling encryption at rest and in transit, regularly patching systems, implementing security groups and network ACLs for network segmentation, using VPNs or Direct Connect for secure network connectivity, and regularly monitoring security logs and alerts.

14. What are SQS and SNS and how do they differ?

    • Answer: SQS (Simple Queue Service) is a message queuing service for asynchronous communication, enabling decoupled architectures. SNS (Simple Notification Service) is a pub/sub messaging service, sending messages to multiple subscribers. SQS handles one-to-one communication while SNS handles one-to-many.

15. Explain the concept of Auto Scaling.

    • Answer: Auto Scaling automatically adjusts the number of EC2 instances in response to demand, ensuring consistent performance and availability. It scales based on metrics like CPU utilization, memory usage, or custom metrics.

16. How do you manage costs in an AWS environment?

    • Answer: Cost management involves using the AWS Cost Explorer, setting up budgets and alerts, right-sizing instances, utilizing reserved instances or Savings Plans, and using services like AWS Cost Anomaly Detection.

17. What are some common AWS security vulnerabilities and how to mitigate them?

    • Answer: Common vulnerabilities include misconfigured security groups, insecure S3 buckets, insufficient IAM permissions, and outdated software. Mitigation involves following security best practices, regularly reviewing configurations, using least privilege access control, and implementing automated security scanning.

18. Explain the different types of AWS networking services.

    • Answer: AWS offers VPCs, subnets, routing tables, security groups, network ACLs, NAT gateways, VPN connections, Direct Connect, Transit Gateway, and other services for network management.

19. Describe your experience with AWS Serverless Application Model (SAM).

    • Answer: [Answer should describe personal experience with SAM, including specific use cases, benefits realized, and challenges overcome. If no experience, honestly state that and mention familiarity with the concept.]

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