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?

缓存控制:max-age=3600到期:2008 年 5 月 15 日星期二 07:19:00 GMT

考虑到每一个都指的是不同的时间点.

解决方案

看到这个答案:

三个.htaccess过期规则之间的区别p><块引用>

如果响应同时包含 Expires 标头和 max-age 指令，ma​​x-age 指令会覆盖 Expires 标头，即使Expires 标头更具限制性.此规则允许源服务器为给定的响应提供更长的到期时间HTTP/1.1(或更高版本)缓存而不是 HTTP/1.0 缓存.这可能是如果某些 HTTP/1.0 缓存不正确地计算年龄或过期时间，可能是由于时钟不同步.

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

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

解决方案

See this answer:

Difference between three .htaccess expire rules

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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