Manual:$wgUseCdn

Details
Enable/disable caching>Special:MyLanguage/Manual:Performance tuning#Page view caching|page view caching. Cdn configuration causes the following changes in behaviour:

Purges are sent to ensure content edited by users remains up to date immediately.
 * The  header is changed to allow the cache proxy to blindly cache content for a predetermined period of time (configured by ).
 * The  header is artificially shortened to ensure the cache proxy will not renew outdated HTML beyond a certain age.  The   date will never be older than .  This will allow to refresh the cached copy in case there were changes to footer icons, sidebar, skin update, and other configuration or skin-level changes not tracked by the wiki page itself.

The list of Cdn servers to be purged on update must be stored in  .