Nginx caching headers

Hello,

Are there any specific reasons why nginx has both ETags and the Last
Modified headers being sent? From my understanding, this is a bit
redundant
for most situations.

Thanks

Posted at Nginx Forum:
http://forum.nginx.org/read.php?2,251441,251441#msg-251441

Hello!

On Wed, Jul 02, 2014 at 11:26:54PM -0400, eiji-gravion wrote:

Are there any specific reasons why nginx has both ETags and the Last
Modified headers being sent? From my understanding, this is a bit redundant
for most situations.

This is required to support both clients using Last-Modified as a
cache validator, and ETag as a cache validator. As nginx doesn’t
know what a client will use, it returns both. (And this is
identical to what other servers out there do.)

Originally ETag support was added to support download resumption
in IE9, it needs strong entity tags to be able to resume
downloads using range requests. And obviously there are lots of
clients which don’t support ETag.


Maxim D.
http://nginx.org/

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