Content Delivery Network
Content Delivery Network
A Content Delivery Network (CDN) is a collection of connected data centers around the world that sit between your web visitor and your server, which we’ll call your origin server. When someone visits your web page the CDN first checks the data center closest to your visitor to see if a cached version of the page or any other resources they requested are available there. If they’re not found in the cache, the data center will relay the request to the origin server which supplies the missing resources to the data center. The data center caches them for future use and sends them on to the web visitor. If the visitor is in luck and the data center has a copy of the page or resource, then it delivers that local copy. That’s usually much faster than asking your origin server to rebuild and serve those resources every time a request is sent. Often the data center has a configurable time to live (TTL) after which it considers the content of its cache stale . Stale content is always refreshed from the origin server when there is a request for it, and the time to live on the content is reset. This allows a balance for resources that are only changed infrequently to remain up to date.
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