You can use the default mode (Respect Existing Headers). In this case, the browser decides how long to cache the files based on the value it receives from the main server. Otherwise, the browser caches the relevant files from 30 minutes to 30 days, depending on the time you choose, and then uploads the latest version of the files from the server.
Note that setting this issue has a big impact on your website and change the amount with enough information.
Read more about Caching: Browser Cache Expiration in our tutorial section.
