AWS Certified SysOps Administrator – Associate — Question 12

A company is running a website on Amazon EC2 instances behind an Application Load Balancer (ALB). The company configured an Amazon CloudFront distribution and set the ALB as the origin. The company created an Amazon Route 53 CNAME record to send all traffic through the CloudFront distribution. As an unintended side effect, mobile users are now being served the desktop version of the website.
Which action should a SysOps administrator take to resolve this issue?

Answer options

• A. Configure the CloudFront distribution behavior to forward the User-Agent header.
• B. Configure the CloudFront distribution origin settings. Add a User-Agent header to the list of origin custom headers.
• C. Enable IPv6 on the ALB. Update the CloudFront distribution origin settings to use the dualstack endpoint.
• D. Enable IPv6 on the CloudFront distribution. Update the Route 53 record to use the dualstack endpoint.

Correct answer: A

Explanation

The correct answer is A because forwarding the User-Agent header allows CloudFront to differentiate between mobile and desktop requests, thus serving the appropriate version of the website. Option B incorrectly suggests adding a User-Agent header as a custom header, which does not address the need for forwarding the header. Options C and D relate to enabling IPv6 but do not resolve the issue of serving the correct version of the website based on the device type.