Push vs. Pull: What’s the Difference?

Like most CDNs, CacheFly offers two distinct methods of caching your files: “push,” which is the traditional upload method, and origin “pull,” also known as reverse proxy.

Here, we will explain the differences so you can understand and select which option will work best for your type of environment.


With CacheFly’s reverse proxy, you define an origin domain where CacheFly will automatically “pull” files from as needed.


For example with the reverse proxy option, the first time an end-user requests a file and it isn’t already loaded on our CDN (this is known as a “cache-miss”), CacheFly will request that file from your origin domain to fulfill the user’s request. This is a seamless process that happens “on the fly.” After CacheFly retrieves the file from your origin domain, future requests for that file will be served from the CDN cache. That’s how reverse proxy/origin pull works.

Updates to previously cached files are determined by your website’s HTTP cache headers (expires or max-age). If you rather not wait for the object to expire, CacheFly allows you the option to purge the file from CDN cache from within the customer portal or via an API call.

Benefits of using a Reverse Proxy/Origin Pull method:

  • Easier to configure
  • Updates content as requested (by a cache miss)
  • Real-time purging of objects (250ms!)
  • Optimal for content providers with high traffic and lots of small files. 


Instead of waiting for the first request from the user to pull and cache files to CacheFly CDN servers, your other option is to simply upload, or “push” your files to ftp.cachefly.com. Your FTP login credentials are displayed on the welcome page of the customer portal. Once you’ve transferred your files to ftp.cachefly.com and your uploading client has issued a disconnect (FTP QUIT), your files will be available from your CacheFly given subdomain.

Updates to previously uploaded objects will be reflected at the edge within a few minutes while new/uncached files will be ready for use shortly after disconnecting from your upload session.

Benefits of using Upload/Push method:

  • Optimal for content providers with large files downloads (e.g. podcasts)
  • No ‘stampede’ effect to origin server
  • Guaranteed QoS for throughput, even on first request
  • No need to purge objects
  • Easily automate uploads using rsync

If you’re still unsure, feel free to contact us at support@cachefly.com. We’re always happy to help you figure out which method of synchronizing your files is right for you.