Caching

Debug a cached response

Inspect freshness, validators, age, and transferred size to explain whether a response came from a browser cache, CDN, or origin.

Open the Network panel and reload a page twice. Select the same static resource after each load.

Look for:

  • Cache-Control and its freshness lifetime
  • ETag or Last-Modified
  • Age, which may reveal time spent in a shared cache
  • a 304 status after conditional validation
  • “memory cache” or “disk cache” in the transferred-size column

Developer tools often include a Disable cache option. It works while the tools are open and is useful for comparing cached and uncached behavior.

Be careful when testing. A hard reload, normal reload, disabled cache, and private window can produce different results. Record exactly which one you used.

Quick check

Result

You got of right.

Lesson completed

Take this course offline

Get every free book, course edition, and software download.

Get the download library →