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MongoDB Realm serves hosted files through a Content Delivery Network (CDN) in order to minimize the latency between receiving a request for a resource and returning the requested resource.
When a client requests a resource that's hosted in Realm, the CDN server that processes the request checks for a cached copy of the file. If the server finds a valid cached copy of the resource, it returns it to the client. Otherwise, it forwards the request to Realm and caches the returned file before returning it to the client.
The CDN caching process decreases the latency for end users when they request a resource but may cause users to receive an out-of-date version of a resource if the file has changed since the CDN server cached it. You can flush the CDN cache in order to make it drop all cached files and start serving the latest version of each file.
The CDN automatically refreshes cached files periodically. You can configure the caching behavior for an individual file by adding a a Cache-Control attribute to the file.