We are launching a new infrastructure feature that dramatically improves the server response time for static images. We call it Media Accelerator (MA). It works by checking HTTP requests at our load balancers and automatically directing requests for static media files to a high performance cluster that's optimized for high speed cached delivery of these files. It works transparently, and no changes are required in your HTML in order to enjoy this new feature. We expect a significant improvement in server response time for static format media files as a result of this improvement. We also expect faster processing of dynamic content such as ASP pages and PHP pages as a result of adding the additional server cluster. Today, only requests for JPG, GIF, PNG, MP3, WAV, WMA, and SWF files are directed to our MA cluster.

1) When files are uploaded (overwritten) using FTP, each file is automatically flushed from all cache servers.
This allows you to overwrite your media files using FTP without having to wait for up to 30 minutes to elapse before the new version of this media file is visible on your web site. Changes to media files will be visible within a few seconds of uploading the new copy using FTP. Note that SFTP uploads do not trigger automatic cache expiration, so if you are overwriting an existing media file, use FTP to upload it if you need it to be immediately available.

2) Cookie information is not stored in the cache.
It's very rare for cookies to be needed for static media file types. If you have a special circumstance that does require cookies for a static image file, you may use a bypass technique for that particular image. See the section below on Cache Bypass Techniques if needed.

3) Files that are protected by "HTTP-Basic" password protection are not cached.
This is done for security reasons. If your content is password protected, then it will bypass the MA cluster, and the media will be served directly from your default cluster.

4) Not all static media files are cached currently.
Only JPG, GIF, PNG, MP3, WAV, WMA, SWF files are cached in our initial release. Additional file types will be added later. If you would like an additional file type to be added, please provide us with that feedback, and we will consider inclusion in a subsequent feature update.

5) By default, media files are cached for 30 minutes.
If no specific Expires header is present, the MA cluster will store the media file for 30 minutes. If an alternate time period is specified in an Expires header, then it will be respected. This technique can be used increase, decrease, or disable MA caching of files by site, file type or by file name. When the expiration of a file is reached it will be automatically replaced in the cache on-demand with a fresh copy. The expiration settings can be controlled by using an .htaccess file with the format described below in the Cache Bypass Techniques section. Note that you may use an .htaccess file with any default cluster technology, including PHP4, PHP5, ASP, .NET, and Ruby.