Fixit – ETag Support

This test determines if your page resources are delivered using valid ETag caching support. ETags allow the browser to better understand which content can be cached and which should be re-validated on each page load.

Checking for ETag support

This test checks to see if HTTP replies include ETag caching information. If invalid ETag data or no ETag data is detected then the test reports a FAIL.

If you receive a FAIL for this test, you should consider enabling support for this feature of HTTP on your web server. On the two most common web servers, Apache and Nginx, ETags are configured to be on by default in recent versions but if you need to alter your configuration we recommend these guides:

• Configuring ETags with Nginx
• Configuring ETags with Apache

Reference

This test is based on a YSlow best practice. See http://yslow.org/faq/ for more details.