SAP-C02 Question 255
Select 3A financial services company is designing a new trading application that requires high reliability for processing transactions. The application is hosted on Amazon EC2 instances in an Auto Scaling group across two Availability Zones (AZs). The company has observed occasional downtime during AZ failures and wants to ensure the application meets reliability requirements by minimizing impact during such events. Which design changes should the Solutions Architect implement to meet the reliability requirements?
- A
Configure the Auto Scaling group to launch instances in at least three Availability Zones.
- B
Enable Elastic Load Balancing (ELB) cross-zone load balancing to distribute traffic evenly across all instances.
- C
Use Spot Instances as 50% of the Auto Scaling group to reduce costs while maintaining reliability.
- D
Implement Amazon RDS Multi-AZ deployments for the application's database.
- E
Configure Auto Scaling health checks to use ELB health checks instead of EC2 instance status checks.
Show answer and explanation
Correct answers: A, B, D
Explanation
To meet the reliability requirements, the architecture should increase fault tolerance and ensure high availability across multiple AZs. Using three AZs for the Auto Scaling group reduces the impact of an AZ failure, while ELB cross-zone load balancing ensures balanced traffic distribution. Amazon RDS Multi-AZ deployments add reliability to the database layer by enabling automatic failover. Spot Instances, while cost-effective, are not suitable for applications requiring high reliability due to the risk of interruptions. Configuring health checks improves instance management but does not directly address AZ-level reliability concerns.
- A. Correct.
Correct: Configuring the Auto Scaling group to use three Availability Zones increases fault tolerance and improves reliability by minimizing the impact of an AZ failure.
- B. Correct.
Correct: Enabling ELB cross-zone load balancing ensures traffic is distributed evenly across all instances in all AZs, reducing the risk of overloading instances in a single AZ.
- C. Incorrect.
Incorrect: While Spot Instances offer cost savings, they are not reliable for critical applications due to potential interruptions. This does not align with the reliability requirements.
- D. Correct.
Correct: Amazon RDS Multi-AZ deployments provide automatic failover for database instances, ensuring high availability and reliability of the database tier.
- E. Incorrect.
Incorrect: Although using ELB health checks can improve instance replacement accuracy, it does not directly address AZ failure scenarios or improve overall reliability.