AWS Certified CloudOps Engineer Associate SOA-C03 Practice Question

A retail company runs its web tier on an EC2 Auto Scaling group behind an Application Load Balancer (ALB) in a single Region. Most traffic consists of unauthenticated requests for identical product-catalog pages, but flash-sale events push the group from 4 to more than 80 instances, sharply increasing cost. The operations team needs a solution that will offload these repeated requests, provide HTTPS for end users, and require no changes to the existing application code. Which approach will meet these requirements while introducing the least operational overhead?

Create an Amazon CloudFront distribution that uses the existing ALB as the origin, forward only the headers needed for personalization, and set an appropriate TTL for catalog pages.
Resize the Auto Scaling group instances to a larger class and enable ALB connection draining to smooth out scale-in events.
Place an Amazon API Gateway HTTP API in front of the ALB and enable API caching to store catalogue responses for a few minutes.
Deploy an Amazon ElastiCache for Redis cluster and modify the application to implement a lazy-loading cache for catalog pages with a short expiration time.

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Answer Description

Placing an Amazon CloudFront distribution in front of the ALB lets CloudFront cache the publicly accessible catalog pages at edge locations. Default, minimum, and maximum TTL settings can be tuned so that only frequently requested pages are cached, while personalized or authenticated traffic can be excluded by forwarding the necessary headers or cookies. Because CloudFront simply points to the existing ALB origin and terminates HTTPS at the edge, no application code changes are needed and the Auto Scaling group sees far fewer requests, reducing cost.

Using ElastiCache would offload reads but requires the application to implement Redis or Memcached calls, adding development effort. API Gateway caching would add another managed service and still leave the ALB in the data path, providing limited benefit and extra configuration complexity. Increasing EC2 instance sizes or enabling connection draining addresses scaling symptoms rather than removing the repeated load, so it does not meet the requirement to offload requests.

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