Looking for a CDN

Most of the CDN's that I've seen require you to upload your content in advance. I'm looking for a CDN that, upon receiving a request for a resource it hasn't seen, will contact my application server. If the application server returns something, it should be sent to the user and then cached in the CDN. If not, it should just return a 404. If the user requests an unexpired item, the CDN should just serve it without bothering my app server.

Does anything like this exist? Is there a way to get Cloudfront to work like this?

From serverfault Bill

• The technology you're looking for is called Origin Pull. I'm not sure about Cloudfront specifically, but most CDNs are able to offer this.

  Alister Bulman : Yep, it's incredibly common. As for the caching or 404's, that's usually up to the origin server to set the appropriate headers, for cache-control & Expires - the CDN will just propagate that.

  XCondE : Try these, in increasing order of cost: CDNetworks, EdgeCache, LimeLight Networks, Akamai.
  From gjb

• You're looking for the Coral CDN, basically. It's dead easy to use, and free!

  John Gardeniers : Certainly easy to use but I just tried it with a couple of simple static web pages and, at least during my brief test, proved to be extremely slow. Five minutes later I'm still waiting for the second page to load.
  From Bill Weiss

• AS mentioned, you want "origin fetch" services from a CDN. SimpleCDN, MaxCDN, Voxel, CacheFly and others offer this at the low end with contract-less pay-as-you-go options. See here for a list of many of these smaller CDNs.

  As for the big boys, Level3, Akamai, and Limeleght offer this with contract-based terms.

  From rmalayter