Amazon CloudFront Lowers Minimum Content Expiration Period
We're excited to announce that you can now use Amazon CloudFront for frequently changing content. Before today, Amazon CloudFront’s edge locations cached objects for a minimum of 60 minutes. Effective today, we’ve removed the sixty minute minimum expiration period (also known as “time-to-live” or TTL) from Amazon CloudFront. With this change, you have the ability to configure a minimum TTL for all objects in your distribution using the Amazon CloudFront API. The minimum TTL value may be as short as 0 seconds. You can then set the TTL for each file by setting the cache control header on your file in the origin. Amazon CloudFront uses cache control headers to determine how frequently each edge location gets an updated version of the file from the origin. Note that our default behavior isn’t changing; if no cache control header is set, each edge location will continue to use an expiration period of 24 hours before checking the origin for changes to that file. You can also continue to use Amazon CloudFront's Invalidation feature to expire a file sooner than the TTL set on that file.
You can learn more about the new expiration period policy in the Amazon CloudFront Developer Guide
or by visiting the Amazon CloudFront