Topic: Unclear caching behaviour

[TK481]

Hello everyone,

I have a webapp setup and using Apache 2.2.17 on a Linux machine. I observed a strange caching behaviour and maybe someone has an idea about it. Basically I'm requesting a page from two client machines several times and check the Apache log afterwards.

Client 1:
request page -> all resources http get 200
request page again -> all resources http get 304 (only exception is php-index which is set to no-store, no-cache, must-revalidate)

Client 2:
request page -> all resources http get 200
request page again -> php-index http get 200, no further log entries

after that I enabled the apache directive ExpiresByType on one resource. Result:

Client 1: no change

Client 2 on second request -> php-index http get 200, expired resource http get 304

Both clients are using Mozilla Firefox 3.6.19 as user agent and using the same network connection (no proxy involved).

I fail to understand the different behaviour of the two clients. The server sets the default expiration date depending on mime type to something like 1 day to 2 weeks. Therefore I would conclude that the behaviour of client 2 is correct since it only requests a resource again if the expiration date is due. However both clients should be identical which leads me to believe that there might be a problem on the server side/configuration.

Any ideas on this topic?

Thanks in advance
TK

[Kanashii]

[PHP]
Cache-Control: no-store, no-cache, must-revalidate
Pragma: no-cache
Expires: Tue, 14 Sep 1999 01:01:01 GMT

[static]
Cache-Control: max-age=2592000, public
Expires: future eq one month date
Age: 23390

[dvdoug]

Do you Vary: User-Agent? If so, it could be https://bugzilla.mozilla.org/show_bug.cgi?id=669001 ?

Clear the cache on the 2nd machine, and see if it starts to behave.