SAA-C03 Question 166
Select 3A company is designing a highly available architecture for their e-commerce application running on AWS. The application consists of a web tier, an application tier, and a database tier. The web and application tiers are stateless, and the database tier must maintain data consistency. How can the company achieve high availability and fault tolerance for this architecture?
- A
Deploy the web and application tiers in an Auto Scaling group across multiple Availability Zones.
- B
Use an Amazon RDS Multi-AZ deployment for the database tier.
- C
Configure an Elastic Load Balancer to distribute traffic across the web tier instances deployed in a single Availability Zone.
- D
Store session state in Amazon S3 to ensure stateless operation of the web and application tiers.
- E
Use Amazon DynamoDB for the database tier instead of Amazon RDS to avoid the need for Multi-AZ.
Show answer and explanation
Correct answers: A, B, D
Explanation
To design a highly available and fault-tolerant architecture, the web and application tiers should be distributed across multiple Availability Zones using Auto Scaling groups, and an Elastic Load Balancer should distribute traffic across these zones. The database tier should use Amazon RDS Multi-AZ deployments to ensure data consistency and availability. Additionally, stateless architectures for the web and application tiers can be achieved by storing session state in Amazon S3 or other external storage solutions.
- A. Correct.
Correct: Deploying the web and application tiers in an Auto Scaling group across multiple Availability Zones ensures high availability and fault tolerance by distributing instances across different zones.
- B. Correct.
Correct: Amazon RDS Multi-AZ deployments provide high availability and fault tolerance by automatically replicating data to a standby instance in a different Availability Zone.
- C. Incorrect.
Incorrect: While an Elastic Load Balancer is essential for distributing traffic, deploying it across a single Availability Zone does not provide high availability. It should distribute traffic across multiple Availability Zones.
- D. Correct.
Correct: Storing session state in Amazon S3 ensures that the web and application tiers remain stateless, which is an important design principle for high availability and fault tolerance.
- E. Incorrect.
Incorrect: Using Amazon DynamoDB can provide high availability, but it may not be suitable if the application requires relational database features like ACID compliance and complex queries. Additionally, it does not eliminate the need for Multi-AZ deployments when using Amazon RDS.