This is part four of our Five Advanced CDN Configurations for the Serious User email blog series.

In the CDN space, maximizing performance means caching every possible object. Thanks to advanced content purging features, along with managing no-cache/no-store, you can now effectively cache objects that were previously seen as “too dynamic”. Having content that was previously requested individually for each user being cached even once or twice can have an enormous impact on performance, and being able to manage TTLs and purge in real-time is an important aspect of that capability.

Content Purging

All CDNs allow users to purge content – meaning to remove assets from the CDN cache with instant purge, ranging from milliseconds to several minutes. Some very large, legacy CDNs can take minutes or even hours to completely remove content from their cache. Making matters worse, they don’t have a means to communicate when the purge is complete.

Beyond looking for instant purge and purge receipts (notifications that the content is 100% not being served globally), purging content based on advanced parameters can greatly improve the customer experience, dramatically improve your internal workflows, and provide you flexibility in how your sites are updated with new content.

Here are four examples of when purging content using Highwinds can quickly and intelligently affect a business:

  1. Utilize purge capabilities for user generated content (UGC) to wipe suspect content from the CDN when take down notices occur.
  2. Advertising networks have a business need to change their JavaScript regularly. This is also critical if you need to pull down poorly performing ads rapidly.
  3. Entertainment sites and news aggregators benefit from purge by tag functionality because they can label content and pull down groups of media or objects without having to do each manually.
  4. For any CMS-managed content, instant purge enables the removal of content as it is updated.

Below you will find four examples of advanced purge workflows offered by Highwinds within its StrikeTracker CDN management console.


The original and likely most familiar of purge types, purge by URL, gives you easy access to deleting content from the cache by its exact location on any host in your account. If you want to delete a single file and know its location this is probably the method you’re looking for.

Purge by URL

The ability to purge from specific cache keys on the URL helps to eliminate a specific sub-version of the file by query string or cache keyed header.

Purge by URL Options


If your aim is to purge your entire host, or a recursive path within that host, purge by path is the workflow you seek.

Purge by Path


Purge by tag empowers you to clear the cache of content that contains one or more of the submitted list of tags as defined by your origin server. Sample tags that can be applied to a purge workflow include:

✔   Purge by tag via CDN console
✔   Purge by tag using API
✔   Purge by tag using cURL

Purge by Tag


Purge by header allows you to purge content with arbitrary cached header characteristics. With this workflow you can purge on ANY header and value pair represented in the cache.

Purge by Header

By separating different use cases into unique workflows we hope to bring clarity and convenience to one of the most frequent procedures our customers perform. These UI enhancements all represent branches of the same tree (RESTful Purge API) and, as such, carry all of the associated features such as instant purge, cache invalidation (soft purge), and purge receipts. In addition to the workflows available in the StrikeTracker UI, Highwinds offers purge functionality by leveraging its APIs.


Highwinds offers purge receipts (as seen below), which informs the user instantaneously when the chosen content has been purged system-wide.

Purge Receipts

No matter which purge-by workflow you choose (based on the specifics of your content needs, configurations, and policies), you can rest assured that your asset has been deleted from the cache and won’t be delivered because you’ll see the clear visual of a purge receipt.

Five Advanced CDN Configurations for the Serious User