`cache-control: max-age=0` in http request

Question

I have one question: suppose in each http request there is a cache-control: max-age=0 header, so each request will go all the way to the origin web server. Does it

Answer 1

from other post: When sent by the user agent

I believe shahkalpesh's answer applies to the user agent side. You can also look at 13.2.6 Disambiguating Multiple Responses.

If a user agent sends a request with Cache-Control: max-age=0 (aka. "end-to-end revalidation"), then each cache along the way will revalidate its cache entry (eg. with the If-Not-Modified header) all the way to the origin server. If the reply is then 304 (Not Modified), the cached entity can be used.

On the other hand, sending a request with Cache-Control: no-cache (aka. "end-to-end reload") doesn't revalidate and the server MUST NOT use a cached copy when responding.

It makes sense and match my result. when cache is not expired in chrome,it will send request to CDN,CDN will query this with if-modified-since with origin ,then serve the end user.