Question #1702
A company is migrating its on-premises three-tier application to AWS. The application uses a single-instance PostgreSQL database and a stateless web tier running on multiple servers. The company must avoid significant application modifications while improving fault tolerance after the migration.
Which combination of steps will meet these requirements? (Choose two.)
Migrate the web tier to Amazon EC2 instances in an Auto Scaling group fronted by an Application Load Balancer.
Migrate the database to Amazon EC2 instances in an Auto Scaling group with a Network Load Balancer.
Migrate the database to an Amazon RDS Multi-AZ deployment.
Migrate the web tier to AWS Fargate containers managed by Amazon ECS.
Migrate the database to Amazon Aurora Serverless.
Explanation
The correct answers are A and C.
- A: Migrating the stateless web tier to EC2 instances in an Auto Scaling group fronted by an Application Load Balancer (ALB) ensures fault tolerance by distributing traffic and automatically replacing unhealthy instances. This requires minimal application changes.
- C: Migrating the PostgreSQL database to Amazon RDS Multi-AZ provides automatic failover, synchronous replication, and high availability without significant application modifications.
Other options are incorrect because:
- B: Databases are stateful and cannot be placed in Auto Scaling groups with a Network Load Balancer (NLB).
- D: While Fargate/ECS is viable, it may require containerization efforts, which the question aims to avoid.
- E: Aurora Serverless might require application adjustments for compatibility, unlike RDS Multi-AZ.
Key Points: Use Auto Scaling + ALB for stateless tiers; RDS Multi-AZ for managed database fault tolerance with minimal changes.
Answer
The correct answer is: AC