In-depth Investigation of CDN: Part 1
Compare Push and Pull CDN models and evaluate which is appropriate for static vs. dynamic content delivery. Explain how multi-tier CDN architectures scale content distribution. Describe how DNS-based routing and Anycast direct client requests to a nearby edge node to reduce latency.
This lesson details CDN models, multi-tier architectures, and strategies for optimizing dynamic content.
Content caching strategies in CDN
To ensure timely updates, CDNs use two primary classifications to retrieve content from origin servers.
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.
Best for: Static content where the origin server decides exactly what to deliver.
Drawback: Inefficient for rapidly changing content, often resulting in redundant pushes.
Pull CDN
In the Pull CDN model, the CDN fetches data from the origin server only when a user requests it. Proxy servers cache the file for a specified duration (time-to-live) to balance capacity and cost.
This model is ideal for serving dynamic content or high-traffic sites where pre-loading all assets is inefficient.
In short:
Push CDN: Maintains more replicas, improving availability for static content.
Pull CDN: Favored for frequently changing content and high traffic loads due to lower storage consumption.
Let’s say you’re managing a website with two distinct content types:
- News feed: Frequently updated articles and blog posts with varying popularity.
- Static assets: Infrequently updated items, including the company logo, website design elements, and product images.
Note: Most content providers use a hybrid of Pull and Push CDN caching approaches.
Dynamic content caching optimization
Dynamic content changes frequently, requiring specific optimization strategies:
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