SOA-C02 Question 75
Single answerA company is running a web application on an Amazon EC2 instance. During peak traffic hours, the application experiences performance degradation due to high CPU utilization. The company wants to address this issue while ensuring that the application remains available to users. Which approach best demonstrates horizontal scaling?
- A
Adding more EC2 instances behind an Elastic Load Balancer (ELB).
- B
Upgrading the existing EC2 instance type to one with more CPU and memory capacity.
- C
Replacing the existing EC2 instance with a larger instance type using Auto Scaling.
- D
Increasing the storage size of the instance's attached EBS volume.
Show answer and explanation
Correct answer: A
Explanation
Horizontal scaling involves adding more resources, such as EC2 instances, to distribute the workload and handle increased traffic. In this scenario, adding more EC2 instances behind an Elastic Load Balancer allows the application to scale out and maintain availability during peak traffic, which is a characteristic of horizontal scaling. Vertical scaling, on the other hand, involves upgrading the specifications of the existing resource, such as selecting a larger EC2 instance type with more CPU and memory.
- A. Correct.
This is the correct answer. Horizontal scaling involves adding more resources, such as instances, to distribute the workload. Using an Elastic Load Balancer ensures traffic is routed efficiently across multiple instances.
- B. Incorrect.
This describes vertical scaling, which involves upgrading the specifications of the existing resource (e.g., CPU or memory), rather than adding additional resources.
- C. Incorrect.
This also describes vertical scaling, as replacing the existing instance with a larger type is effectively upgrading the current resource.
- D. Incorrect.
Increasing EBS volume size addresses storage limitations but does not resolve CPU utilization issues or improve application availability during high traffic.