[轉載] Defining optimal Cache-Control policy Back
Follow the decision tree above to determine the optimal caching policy for a particular resource, or a set of resources used by your application. Ideally, you should aim to cache as many responses as possible on the client for the longest possible period, and provide validation tokens for each response to enable efficient revalidation.
| Cache-Control directives | Explanation |
|---|---|
| max-age=86400 | Response can be cached by browser and any intermediary caches (i.e. it is "public") for up to 1 day (60 seconds x 60 minutes x 24 hours) |
| private, max-age=600 | Response can be cached by the client's browser only for up to 10 minutes (60 seconds x 10 minutes) |
| no-store | Response is not allowed to be cached and must be fetched in full on every request. |
According to HTTP Archive, amongst the top 300,000 sites (by Alexa rank), nearly half of all the downloaded responses can be cached by the browser, which is a huge savings for repeat pageviews and visits! Of course, that doesn't mean that your particular application will have 50% of resources that can be cached: some sites can cache 90%+ of their resources, while others may have a lot of private or time-sensitive data that can't be cached at all.
Audit(審查) your pages to identify which resources can be cached and ensure that they are returning appropriate Cache-Control and ETag headers.