AWS Certified Solutions Architect – Professional — Question 448

A customer has a website which shows all the deals available across the market. The site experiences a load of 5 large EC2 instances generally.
However, a week before Thanksgiving vacation they encounter a load of almost 20 large instances. The load during that period varies over the day based on the office timings.
Which of the below mentioned solutions is cost effective as well as help the website achieve better performance?

Answer options

• A. Setup to run 10 instances during the pre-vacation period and only scale up during the office time by launching 10 more instances using the AutoScaling schedule.
• B. Keep only 10 instances running and manually launch 10 instances every day during office hours.
• C. During the pre-vacation period setup 20 instances to run continuously.
• D. During the pre-vacation period setup a scenario where the organization has 15 instances running and 5 instances to scale up and down using Auto Scaling based on the network I/O policy.

Correct answer: A

Explanation

Using AutoScaling scheduled scaling to increase the instance count from 10 to 20 during predictable office hours is highly cost-effective and ensures performance during peak times. Keeping 20 or 15 instances running constantly (Options C and D) results in unnecessary costs during off-peak hours when traffic is low. Manually launching instances (Option B) is inefficient, error-prone, and does not leverage AWS automation capabilities.