A)Refresh
Refresh means that after submitting URL refresh or directory refresh request, the cache content of CDN node will be forced to expire. When you request resources from CDN node, CDN will directly go back to the source station to get the corresponding resources, return them to you, and cache them. The refresh function will reduce the cache hit rate.
We also provide a refresh service, so when a new resource is updated to the source server, you can manually perform the refresh action to ensure that the user sees the latest version of the resource and will not expire.
B) Prefetch
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 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.
