What is an origin server?
The origin server is where your site is actually generated or stored. A CDN fetches from it on a miss and serves cached copies otherwise.
The origin server is the server that holds or generates the authoritative version of your pages, behind the CDN. It might be an application server, a serverless function or a storage bucket. A CDN fetches from the origin on a cache miss or a revalidation, and serves its cached copy otherwise, so the origin sees only part of the traffic.
visitor -> CDN PoP -> (miss) -> origin
visitor -> CDN PoP -> (hit) served from cacheHow much traffic the origin sees depends on the cache hit ratio. After a purge, that share jumps, because every page is a miss until it is cached again.
- Tiered caching and origin shields reduce the number of locations that call the origin.
- Request collapsing merges concurrent misses for the same object into one origin request.
- Cache warming moves the post-deploy misses to a controlled moment, at a rate you choose.
Related terms
References
- MDN: HTTP cachinghttps://developer.mozilla.org/en-US/docs/Web/HTTP/Guides/Caching
- Cloudflare: Tiered Cachehttps://developers.cloudflare.com/cache/how-to/tiered-cache/
- Amazon CloudFront: Origin Shieldhttps://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/origin-shield.html
Warm your cache after every deploy
sitewarm requests the pages in your sitemap after a deploy and reports the cache state the CDN returns for each one, with the vantage point it was measured from.