Prefetching instructs edge servers to retrieve content from the origin, such as images and scripts embedded in HTML content, at the same time as HTML is served to the browser rather than waiting for the browser to request these objects. This can significantly decrease the time it takes to load and display the embedded content.
Prefetch comprises two features:
Prefetch objects. This feature specifies the parent HTMLs or container pages that will contain calls to the embedded HTML content, the prefetchable objects.
Prefetchable objects. This specifies the child objects to be pre-fetched when the parent is served to the browser.
You configure these options separately. For example, you might create a rule setting
www.example.com/my_content/index.html to be a prefetch object. And you might create another rule setting
www.example.com/images/*.jpg as prefetchable objects.
You can apply prefetching to either cacheable or un-cacheable content. When used for cacheable content, and the object to be prefetched is already in cache, the object is moved from disk into memory so that it is ready to be served.
When used for uncacheable content, Prefetching causes the retrieved objects to be uniquely associated with the client browser request that triggered the prefetch so that these objects will not be served to a different end user.
It is strongly recommended that you use the Tiered Distribution feature along with Prefetched content to avoid bursts of requests at your origin.
Prefetching content using Zone Apex Mapping (ZAM) is not supported.
This behavior doesn't include any options. Specifying the behavior itself enables it.
Updated 10 months ago