title: cache-control not working without etag
body: <p>I am sending the following header in the reponse. <code>"Cache-Control: public, max-age=300"</code>, but still every time I hit refresh I get a <code>200</code> response(the request is made to he server again). Same happens if I add the "Expires" header.</p>
  
  <p>But if I add a ETag to the headers, then I get <code>304</code> on refresh(the request goes to the server, the server prepares the response, then matches the ETag and returns a <code>204</code> response).</p>
  
  <p>What should I change so that <code>"Cache-Control"</code> header is used and the 
  content is served from local cache and no request is sent to the server until the age becomes more than <code>"max-age"</code>?</p>
  
  <p>EDIT: Here is an image that doesn't get cached <a href="https://image-dev-dot-quizizz-dev.appspot.com/resource/gs/quizizz-image/rejected.jpeg" rel="nofollow noreferrer">https://image-dev-dot-quizizz-dev.appspot.com/resource/gs/quizizz-image/rejected.jpeg</a></p>