AWS Scenario based interview question and answer

By | July 15, 2023


You have a web application running on an EC2 instance, and you want to ensure high availability and fault tolerance. How would you achieve this using AWS services?

AWS Questions & Answers

AWS Interview Questions and Answers


To ensure high availability and fault tolerance for the web application running on an EC2 instance, you can follow these steps using AWS services:

  • Implement Auto Scaling: Set up an Auto Scaling group to automatically adjust the number of EC2 instances based on traffic demand. This ensures that your application can handle varying loads and provides fault tolerance by replacing unhealthy instances.
  • Use Elastic Load Balancing (ELB): Configure an ELB, such as Application Load Balancer (ALB) or Network Load Balancer (NLB), to distribute incoming traffic across multiple EC2 instances. This improves scalability and provides fault tolerance by automatically routing traffic to healthy instances.
  • Set up Multi-AZ Deployment: Launch EC2 instances in multiple Availability Zones (AZs). This provides fault tolerance in case of a failure in one AZ, as the application traffic will be automatically routed to instances in a different AZ.
  • Implement Database Replication: If your application uses a database, use services like Amazon RDS or Amazon Aurora with Multi-AZ deployment and automated backups to ensure data redundancy and fault tolerance.
  • Use Amazon S3 for Static Content: Offload static content, such as images or CSS files, to Amazon S3. This improves performance and reduces load on the EC2 instances.
  • Enable Cross-Region Replication: If high availability across regions is required, replicate your application infrastructure in multiple AWS regions using services like AWS CloudFormation or AWS Elastic Beanstalk.
  • Implement Monitoring and Alerts: Use Amazon CloudWatch to monitor the health and performance of your EC2 instances, ELB, and other resources. Set up alarms to notify you of any performance or availability issues.
  • Enable Multi-AZ RDS Read Replicas: If you are using Amazon RDS, create read replicas in different AZs to distribute the read workload and provide fault tolerance for the database.
  • Implement CDN: Utilize a content delivery network (CDN) like Amazon CloudFront to cache and serve static content from edge locations closer to the users, reducing latency and improving performance.
  • Use AWS Route 53 for DNS: Configure DNS using AWS Route 53 to distribute traffic across multiple regions or AZs and implement health checks to automatically route traffic away from unhealthy instances.

By implementing these measures, you can ensure high availability and fault tolerance for your web application, providing a seamless experience for your users and minimizing downtime.

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