Updating cached headers
All modern browsers support Cache-Control, so that's all you need.
The server generates and returns an arbitrary token, which is typically a hash or some other fingerprint of the contents of the file.
For example, a user's browser can cache an HTML page with private user information, but a CDN can't cache the page.
This directive specifies the maximum time in seconds that the fetched response is allowed to be reused from the time of the request.
Find your favorite server in the list, look for the appropriate settings, and copy/confirm that your server is configured with the recommended settings.
From a performance optimization perspective, the best request is a request that doesn't need to communicate with the server: a local copy of the response allows you to eliminate all network latency and avoid data charges for the data transfer.First, the browser checks the local cache and finds the previous response.