What is LSCache Check?

The LSCache Check tool allows you to validate whether LiteSpeed Cache is supported on your website. It also determines whether your site is using LiteSpeed Web ADC, or QUIC.cloud CDN.

If LiteSpeed Cache is supported, the tool will also check for configurations that may interfere with LSCache. If found, a stale cache warning will be displayed.

What does LiteSpeed Cache do?

LiteSpeed Cache (LSCache) is a built-in, high-performance dynamic content acceleration feature of LiteSpeed server products.

LSCache accelerates dynamic content (not just PHP pages), with features very similar to those in Apache mod_cache, using an efficient, highly customizable, native implementation within the LiteSpeed server, which greatly reduces page load time and server load.

LSCache eliminates the extra reverse-proxy layer(s) required by add-on cache packages (such as Varnish), providing faster, more efficient handling of static content in addition to its stellar handling of dynamic content.

How is LSCache usage detected?

The LSCache Check tool looks for the following response headers:

  • x-litespeed-cache
  • x-lsadc-cache
  • x-qc-cache

The x-litespeed-cache header is generated by a LiteSpeed web server product such as LiteSpeed Enterprise or OpenLIteSpeed. It shows that LSCache is active, and provides further details, including whether the page was successfully cached.

The other two headers are similar to x-litespeed-cache, but they indicate that LSCache is in use via a different LiteSpeed product.

If the x-lsadc-cache header is present, it indicates that the site is served from LiteSpeed Web ADC.

The x-qc-cache header indicates that the site is using QUIC.cloud CDN.

What does the Stale Content warning mean?

Content is considered “stale” if the page has expired in cache or has been replaced by a newer version. The risk of serving stale content is low with LSCache. LiteSpeed’s intelligent smart tagging system ensures that all related content is purged out of the cache whenever a page changes.

If you have browser cache enabled for dynamic requests (like HTML pages), or if you have a CDN that caches dynamic content, these caches are accessed instead of making a request to LiteSpeed server. As such, they will be unaware that the content on the origin server may have changed. Serving pages from these types of caches always runs the risk of stale content.

We recommend disabling browser cache for HTML pages, and forgoing your CDN’s dynamic cache options. Leave the cache management to LiteSpeed and get the freshest possible content.

Learn more about LSCache at LSCache.io.