SAA-C03 Question 165
Select 2A company runs a web application on a fleet of Amazon EC2 instances behind an Application Load Balancer (ALB) in a single Availability Zone. The application is mission-critical, and the company wants to improve its fault tolerance and ensure high availability. What changes should the Solutions Architect recommend to meet these requirements?
- A
Add a second Availability Zone to the load balancer's target group.
- B
Replace the Application Load Balancer with a Network Load Balancer.
- C
Launch additional EC2 instances in the same Availability Zone.
- D
Enable Auto Scaling across multiple Availability Zones.
- E
Deploy an Amazon RDS instance with Multi-AZ enabled for the database tier.
Show answer and explanation
Correct answers: A, D
Explanation
To design a highly available and fault-tolerant architecture, you need to minimize single points of failure. Adding a second Availability Zone to the load balancer’s target group ensures redundancy in case of an Availability Zone failure, while enabling Auto Scaling across multiple Availability Zones ensures the application can dynamically adjust to traffic demands and remain available. These changes together enhance fault tolerance and high availability for the web application.
- A. Correct.
Adding a second Availability Zone to the load balancer's target group increases fault tolerance and high availability by distributing traffic across multiple zones. This is a best practice for highly available architectures.
- B. Incorrect.
Replacing the Application Load Balancer with a Network Load Balancer is not necessary in this scenario. An ALB is suitable for web applications, and switching to an NLB does not inherently improve fault tolerance or availability.
- C. Incorrect.
Launching additional EC2 instances in the same Availability Zone does not improve fault tolerance. If the Availability Zone becomes unavailable, all instances in that zone will still be affected.
- D. Correct.
Enabling Auto Scaling across multiple Availability Zones ensures that the application can respond to changes in demand and remain highly available, even if one Availability Zone becomes unavailable.
- E. Incorrect.
While using Amazon RDS with Multi-AZ can improve fault tolerance for the database tier, the question specifically focuses on the web application tier. Adding this option does not address the web application’s fault tolerance or availability directly.