AWS Certified Solutions Architect – Associate (SAA-C02) — Question 633

An application calls a service run by a vendor. The vendor charges based on the number of calls. The finance department needs to know the number of calls that are made to the service to validate the billing statements.
How can a solutions architect design a system to durably store the number of calls without requiring changes to the application?

Answer options

• A. Call the service through an internet gateway.
• B. Decouple the application from the service with an Amazon Simple Queue Service (Amazon SQS) queue.
• C. Publish a custom Amazon CloudWatch metric that counts calls to the service.
• D. Call the service through a VPC peering connection.

Correct answer: C

Explanation

Publishing a custom Amazon CloudWatch metric allows the system to track and durably store the count of API calls made to the vendor service without needing to modify the application's core logic. Options A and D only address network routing and do not provide a mechanism for counting or storing call frequency. Option B would require architectural changes to the application to integrate with Amazon SQS, which violates the constraint of not requiring changes to the application.