Your Company Wants to Perform A/B Testing on a New

Your Company wants to perform A/B testing on a new website feature for 20 percent of its users. The website uses CloudFront for whole site delivery, with some content cached for up to 24 hours. How do you enable this testing for the required proportion of users while minimizing performance impact?

A) Configure the web servers to handle two domain names. The feature is switched on or off depending on which domain name is used for a request. Configure a CloudFront origin for each domain name, and configure the CloudFront distribution to use one origin for 20 percent of users and the other origin for the other 80 percent.
B) Configure the CloudFront distribution to forward a cookie specific to this feature. For requests where the cookie is not set, the web servers set its value to ''on" for 20 percent of responses and "off" for 80 percent. For requests where the cookie is set, the web servers use Its value to determine whether the feature should be on or off for the response.
C) Create a second stack of web servers that host the website with the feature on. Using Amazon Route53, create two resource record sets with the same name: one with a weighting of "1" and a value of this new stack; the other a weighting of "4" and a value of the existing stack. Use the resource record set's name as the CloudFront distribution's origin.
D) Invalidate all of the CloudFront distribution's cache items that the feature affects. On future requests, the web servers create responses with the feature on for 20 percent of users, and off for 80 percent. The web servers set "Cache-Control: no-cache" on all of these responses.