Try to fetch a page which is changing at each request (random number
in PHP, apache status, ...)

If the page is catched, it won't change when you request it to nginx.
It will changes after it expires. You can add the
$upstream_cache_status variable, it should log information about cache
status (MISS = the page is not in cache and it's been requested to
backend / HIT = the page has been served from cache / EXPIRED = the
page has expired and it's been requested to backend)

++ Jerome

2009/8/31 fredericsidler <nginx-forum@nginx.us>:
> I'm trying to use nginx with caching capabilities. And I don't know how to test if nginx is really caching files and using them. I can see the files that nginx is caching, but I don't know if it uses them when I request the same URL again.
>
> Posted at Nginx Forum: http://forum.nginx.org/read.php?2,5363,5363#msg-5363
>
>
>