Dynamic Media assets are cached by the CDN (Content Delivery Network) for fast delivery to your customers. However, when you make updates to those assets, you want those changes to take effect immediately on your website. Purging or invalidating the CDN cache lets you quickly update assets that are delivered by Dynamic Media. Instead of waiting for the cache to expire using a TTL (Time To Live) value (default is ten hours), you can send a request from within Dynamic Media to have the cache expire within minutes.
To invalidate your CDN cached content for Dynamic Media assets:
Go to the image you have updated and click on the url button
On click of url, a popup will show up with the Dynamic media url for that specific variation.
Copy this url and navigate to Tools > Assets > CDN Invalidation. Click on CDN Invalidation
Manually add or paste full URL paths to Dynamic Media assets which you copied earlier in the url text. Note: You can invalidate up to 1000 URLs at a given time. Each url that you add must be on its own line.
Near the upper-right corner of the page, select Next.
On the Confirm page, in the URLs list box, you can see a list of one or more URLs of the assets you just added. If necessary, select X to the right of a URL to delete it from invalidation process
Near the upper-right corner of the page, select Submit to begin the CDN invalidation process.