How CDN Works at Pressable
Please Note: With our Edge Cache functionality now available, we recommend using Edge Cache instead of the Pressable CDN (only one should be activated on a site, not both).
All Pressable sites can activate our Content Delivery Network (CDN). Our CDN has a global network of points of presence (PoPs). These PoPs allow us to deliver content to your site’s visitors from a server nearest them.
How Pressable’s CDN Caching Works
Pressable’s CDN caches static assets with the following file extensions: jpg, jpeg, gif, png, webp, css, bmp, js, woff2, ico file type.
By default, the cache-control header is set to 7 days, meaning that browsers receive a directive to store the file for 7 days. This time period can be changed to 10 years.
The CDN only caches static assets. It does not cache pages, nor does it cache data from the database.
Pressable rewrites URLs pointing to the aforementioned assets on page load. The URL used is based on the following format: ######.v2.pressablecdn.com. At this time, it is not possible to use Pressable’s CDN with a custom domain or the primary domain assigned to a site.
Enabling and Disabling the Pressable CDN
Note: Generally, it is not recommended to utilize multiple CDNs on a single site. For example, Jetpack’s free Site Accelerator CDN options and the Pressable CDN should not be enabled at the same time. Edge Cache and the Pressable CDN should also not be enabled at the same time.
To activate or deactivate the CDN on your site, follow these steps.
- Locate the site you want to enable or disable the CDN on within your MyPressable Control Panel Sites List and navigate to Settings → Performance → CDN.
- Click on the toggle switch button within the CDN card (Off or On).
- The CDN will start caching assets and automatically replacing asset URLs within page and post content. Due to page and edge caching, it may take some time to see the change in terms of asset URLs and performance.
The CDN cannot be used on sites without an assigned custom domain.
For performance enhancements, we recommend enabling Edge Cache as an alternative.
How to Purge and Flush the CDN Cache
In some cases, a site administrator or developer may want to purge the CDN of cached version of assets such as older CSS, JavaScript, or image files. This can be done via the following steps.
- Locate the site you want to flush the CDN cache on within your MyPressable Control Panel Sites List and navigate to Settings → Performance → CDN
- Click the Purge button under the CDN card.
- Once purged, this will flush the static assets currently cached across Pressable’s CDN servers.
Frequently Asked CDN Questions
Generally, it is not recommended to utilize multiple CDNs on a single site. The Jetpack Site Accelerator CDN options and Pressable CDN should not be used together.
You cannot flush the Jetpack CDN. If you need the ability to periodically flush the CDN cache.
The Jetpack Image CDN (formerly Photon) will generate WebP image files on the fly and also performs other image processing and optimizations that the Pressable CDN does not.
Jetpack’s Static Asset CDN may not serve all theme and plugin CSS and JavaScript files.
We recommend reviewing Jetpack’s documentation for more Site Accelerator CDN features and limitations.
Edge Cache can eliminate the need for static asset CDNs on some sites, and the Pressable CDN should NOT be used with Edge Cache enabled. For other CDNs, testing may be necessary to determine what works best on each site. For well-cached pages and assets, enabling a CDN while Edge Cache is active may lead to unnecessary additional HTTP requests.
It shouldn’t be necessary to set your site’s Pressable CDN URL within a plugin’s CDN option. The Pressable CDN does not support certain assets such as PDFs and SVG files and forcing assets to use the Pressable CDN URL may lead to conflicts. Additionally, the CDN URL may change if a site is cloned, migrated, or synced to another site. If WP Rocket’s CDN options are used, it is necessary to adjust it so that it does not change the URLs for PDF and SVG files.
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