Chrome browser is not sending if-modified-since header to server

Question

I have these headers being sent to the client by the server:

Cache-Control:private
Connection:keep-alive
Content-Encoding:gzip
Content-Type:text/html
Date:Su         


        

Answer 1

In my experience you need more than just the "Private" Cache-Control header. You need either "Max-Age" or "Expires" to force Chrome to revalidate content with the server.

Remember that revalidation will only start after these time values have elapsed, so they may need to be set to a small value.