Amazon announced that you can now configure Amazon CloudFront to use only a specific set of HTTP query parameters to be used as the cache key, while still forwarding all the parameters to the origin through a feature called Query String Whitelisting.
Previously, customers could configure Amazon CloudFront to use all the query strings parameters as part of the cache key as well as forward them to the origin. This allowed customers to vary the content based on all these query parameters and allowed them to speed up dynamic, personalized content for their end users. With query string whitelisting, customers can now choose the query parameters that Amazon CloudFront should use for its cache key while still forwarding all query parameters to the origin. Customers now get further benefits for accelerating dynamic content due to higher cache-hit ratios and a reduced load on the origin by actively avoiding certain parameters (e.g., session ID) that are used by Amazon CloudFront to form the cache key.