Improving performance with browser caching

On requests, check that you are using browser caching.

Last-Modified should be set.
Expires should be set (seems to be dynamically set if max-age is set on cache-control).
On cache-control - watch out for must-revalidate - this seems to bypass the cache.

This is not good:-
Cache-Control max-age=0

This is OK:-
Cache-Control max-age=1800, public, must-revalidate

NB, public is to allow caching on SSL links.

This is BEST:-
Cache-Control max-age=18000, public

Are the flash files cached?