Expires vs max-age，如果两者都在HTTP响应中声明，哪一个优先？ [英] Expires vs max-age, which one takes priority if both are declared in a HTTP response?

问题描述

如果HTTP响应同时返回Expires和max-age指示使用哪一个？

If a HTTP response that returns both Expires and max-age indications which one is used?

Cache-Control: max-age=3600
Expires: Tue, 15 May 2008 07:19:00 GMT

考虑到每个人都指的是不同的时间点。

Considering that each one refers to a different point in time.

推荐答案

看到这个答案：

三个.htaccess到期规则之间的差异

如果响应包含Expires标头和max-age指令，
max-age指令覆盖Expires标头，即使
Expires标头更具限制性。对于给定的响应，此规则允许源服务器
为
HTTP / 1.1（或更高版本）缓存提供比HTTP / 1.0缓存更长的到期时间。如果某些HTTP / 1.0缓存不正确地计算年龄或
到期时间，这可能是
有用，可能是由于时钟不同步。

If a response includes both an Expires header and a max-age directive, the max-age directive overrides the Expires header, even if the Expires header is more restrictive. This rule allows an origin server to provide, for a given response, a longer expiration time to an HTTP/1.1 (or later) cache than to an HTTP/1.0 cache. This might be useful if certain HTTP/1.0 caches improperly calculate ages or expiration times, perhaps due to desynchronized clocks.

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