CDN Prefetching is warming the CDN cache for the purpose of speeding up content delivery for those first users who would otherwise get a slow 'cache miss' response, because the CDN first needs to fetch the file from the origin server. Another potentially large benefit of CDN Prefetching is origin offload: the origin gets less requests and consequently it's less likely your origin server and/or network will fall over or become really slow.
Prefetching is beneficial if you use the CDN to deliver large files and you expect new content (for example a new software download) to be requested by many users at the same time directly after publishing.
Verizon / EdgeCast has a 'Load to Edge' feature including an API, but most CDNs do not provide a way to have the caches prefetch content from origin.
Read on to learn more about the differences between CDNs.
Does the prefetching start instantly or is there a (significant) delay?
Is prefetching free or do you pay for using the feature (e.g. pay X for every 1000 prefetch requests)? Does the CDN charge for ingress data transfer (origin to CDN)?
Does the CDN provide an API for loading content to their edge servers?
When prefetching, is the content loaded to all POPs?
CDNs and Prefetch
- = Yes
- = Sort of/partially
- = No
- = Extra costs
- = Unknown
More info per CDN
Limelight has a product/feature called Intelligent Ingest that allows for automated upload into Limelight's Origin Storage Services.
Prefetch is available via the UI and API and available to all customers at no extra costs (Limitation: max 100 requests per day). On request, Kingsoft Cloud can enable 'background cache fill'.
Prefetch is available via the UI and API and available to all customers at no extra costs. On request, BaishanCloud can enable 'background cache fill'.
More info in their How to Prefetch Files article.
Verizon Digital Media Services
Content may be loaded to the entire network or solely to specific regions. Loading by region provides the means through which cache optimization may be targeted to regions where demand is highest. Regions are North America, US East, US Central, US West, Europe, Asia, South America. The default limit is 50 concurrent load requests at any given time. API is available. The Prefetch usually starts ~ 5 minutes after submitting the request.
Akamai does not provide prefetching functionality, but the following two community articles contain useful info: Content Pre-loading / pre-warming at Akamai. Media Content Pre-loading / pre-warming at Akamai. Both articles are a bit old though (2015).
There is a limit of 2000 URLs per request and 60 requests per 5 minutes for each customer account in both Purge and Prefetch. How can I Purge or Prefetch files?
More CDN Guides