Question #566
A company is migrating a three-tier Java web application from an on-premises environment to AWS after experiencing downtime due to a traffic surge. The application has a dependency on a PostgreSQL database. A solutions architect must design a scalable and highly available solution to support 250,000 daily users. Which steps should the solutions architect take?
Use Amazon EC2 instances in an Auto Scaling group behind a Network Load Balancer (NLB) deployed across two Availability Zones for the web tier. Use Amazon RDS for PostgreSQL in a Single-AZ configuration with automated backups enabled. Configure an Amazon Route 53 weighted routing policy to distribute traffic between EC2 instances.
Use AWS Elastic Beanstalk to deploy the web tier with an environment configured with an Application Load Balancer (ALB) and an Amazon EC2 Auto Scaling group across two Availability Zones. Provision an Amazon RDS PostgreSQL Multi-AZ DB instance. Configure an Amazon Route 53 alias record to route traffic from the company\u2019s domain to the ALB.
Use AWS CloudFormation to deploy a stack that includes an Application Load Balancer (ALB) in front of an Amazon EC2 Auto Scaling group spanning three Availability Zones. The stack provisions a Multi-AZ Amazon Aurora PostgreSQL DB cluster with a Retain deletion policy. Use an Amazon Route 53 alias record to direct traffic from the company\u2019s domain to the ALB.
Use AWS Elastic Beanstalk to create a web server environment spanning two AWS Regions, each with an Application Load Balancer (ALB). Deploy a Multi-AZ Amazon Aurora PostgreSQL DB cluster with a cross-Region read replica. Use Amazon Route 53 with a latency-based routing policy to distribute traffic between the two Regions.
Explanation
Answer B is correct because:
1. High Availability: The EC2 Auto Scaling group spans three AZs (better than two AZs in other options), ensuring redundancy. The Multi-AZ Aurora PostgreSQL cluster provides automated failover and read replicas for scalability and HA.
2. Scalability: Aurora PostgreSQL outperforms RDS in scalability, and Auto Scaling handles traffic surges.
3. Infrastructure as Code: CloudFormation ensures repeatable deployments, and the Retain policy safeguards the database during stack deletions.
4. Route 53 Integration: Directing traffic to the ALB ensures efficient load distribution.
Why other options are incorrect:
- A: Uses only two AZs for the web tier and RDS PostgreSQL (less scalable than Aurora).
- C: Overcomplicates with multi-region deployment, which is unnecessary unless specified.
- D: Uses Single-AZ RDS (no HA) and NLB (less suited for HTTP traffic than ALB).
Key Points:
- Always use Multi-AZ databases (Aurora preferred) for HA.
- Distribute workloads across ≥3 AZs for resilience.
- ALB + Auto Scaling handles web tier scalability.
Answer
The correct answer is: B