Proxy Web Servers and Authentication > How Proxies Work > Cache control

Cache control request directives

no-cache

Requests an end-to-end revalidation -- the origin server should be reached through the chain of proxies to determine whether the entity is up-to-date.

no-store

An intermediate proxy must not store any part of the request or response on non-volatile (e.g. disk) media.

max-age=seconds

The client specifies a maximum age of the entity (in seconds) that it will accept out of a proxy's cache before the origin server must be contacted.

max-stale

The client specifies that it is willing to accept an entity that the cache has determined is past its freshness lifetime.

max-stale=seconds

As above, but the client specifies a maximum number of seconds beyond a freshness lifetime.

min-fresh=seconds

The client requires that the entity in the proxy cache must have at least the specified number of seconds left before the freshness lifetime expires.

only-if-cached

Requests that the proxy return the entity only if it can be served from the proxy's cache.