Expires vs max-age, which one takes priority if both are declared in a HTTP response?

Question

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.

score 58 · Accepted Answer · edited May 23 '17 at 10:31

58

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.

edited May 23 '17 at 10:31

Community

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answered Sep 26 '11 at 00:23

Peter O.

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Is it that only in Apache or it is a general rule? Thanks. – vtortola Sep 26 '11 at 00:25
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This applies in general; the paragraph above comes from section 14.9.3 of the HTTP/1.1 specification. – Peter O. Sep 26 '11 at 00:26

score 14 · Answer 2 · answered Dec 06 '13 at 08:54

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This case is explained in the official RFC on W3C.

The max-age directive takes priority over Expires

answered Dec 06 '13 at 08:54

Cybermaxs

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Expires vs max-age, which one takes priority if both are declared in a HTTP response?

2 Answers2

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