By adding Cache-Control: no-cache to the response along with Last-Modified and ETag — as shown below — the client will receive a 200 OK response if the requested resource has been updated, or will otherwise receive a 304 Not Modified response if the requested resource has not been updated. http. HTTP/1.1 200 OK Content-Type: text/html …
https://developer.mozilla.org/en-US/docs/Web/HTTP/Guides/Caching



