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Cache-Control: no-cache, no-store, must-revalidate. This instructs the browser or an intermediate caching server not to store any static files. no-store means do not store particular resource from the server anywhere (i.e browser or proxy caching ).
The must-revalidate response directive indicates that the response can be stored in caches and can be reused while fresh. If the response becomes stale, it must be validated with the origin server before reuse. Typically, must-revalidate is used with max-age .
The must-revalidate directive ought to be used by servers if and only if failure to validate a request on the representation could result in incorrect operation, such as a silently unexecuted financial transaction.
The no-cache directive means that a browser may cache a response, but must first submit a validation request to an origin server.
I believe that must-revalidate means :
Once the cache expires, refuse to return stale responses to the user even if they say that stale responses are acceptable.
Whereas no-cache implies :
must-revalidateplus the fact the response becomes stale right away.
If a response is cacheable for 10 seconds, then must-revalidate kicks in after 10 seconds, whereas no-cache implies must-revalidate after 0 seconds.
At least, that's my interpretation.
max-age=0, must-revalidate and no-cache aren't exactly identical. With must-revalidate, if the server doesn't respond to a revalidation request, the browser/proxy is supposed to return a 504 error. With no-cache, it would just show the cached content, which would be probably preferred by the user (better to have something stale than nothing at all). This is why must-revalidate is intended for critical transactions only.
With Jeffrey Fox's interpretation about no-cache, i've tested under chrome 52.0.2743.116 m, the result shows that no-cache has the same behavior as must-revalidate, they all will NOT use local cache when server is unreachable, and, they all will use cache while tap browser's Back/Forward button when server is unreachable.
As above, i think max-age=0, must-revalidate is identical to no-cache, at least in implementation.
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