In-Depth Investigation of CDN: Part 1

A CDN must decide what to cache, where to keep it, and how a client finds a suitable copy. These decisions interact: routing to a nearby empty cache can still require a long trip to the origin.

Content caching strategies in CDN

Push and pull describe how content reaches a cache. They do not, by themselves, determine freshness or how many replicas exist.

Push CDN

In the Push CDN model, the origin server automatically sends content to the proxy servers. The content provider is responsible for managing this delivery.

• Useful when: The publisher knows which objects will be needed and wants them available before the first request.

• Tradeoff: Sending objects to locations that never request them consumes bandwidth and storage. Frequent updates can increase that waste.

Pull CDN