The role of a CDN is to cache content close to your end users, so that your web and mobile applications can load fast everywhere. The CDN also acts as a buffer between your users and your hosting infrastructure to avoid performance hits or even downtime in times of traffic bursts.

By default, the servers of Filerobot's CDN (Points of Presence) cache optimized media assets for up-to 30 days. This means that the CDN servers will not try to fetch the origin asset for up-to 30 days. If the origin asset is modified without changing its filename (versioning) or invalidation, the "old" asset will still be served when calling a Filerobot CDN URL, such as **//{folder/{filename?w=400**}

The 30-day caching period can be customized in the Settings of the Filerobot Admin:

We do not recommend to reduce the default caching period under 7 days to leverage the full power of CDN caching and serve fast media everywhere.