nginx cache as reverse proxy.

[David Taveras]

Hello,

I would like to know if I dont set any time in proxy_cache_valid ,
will nginx base the amount of time it should cache a file from the
proxied server response header "Expires Cache-Control" ?

Also, once I have this set does turning on the cache mean that if
gifs/jpgs/txt/html files have a long expiry period of time in them
from the proxied server .. does that mean that nginx will make ZERO
requests to that server.. or would it still have ti fetch the HEADER
of those files every time just to check if it has changed?

Objective:
Trying to configure the cache on nginx to read the png/gif/html/txt
header once and NOT many ANY rquest to the backend server for that
file (not even a head request) for the time being the Cache Expire
control for that particular file is valid.



Thanks

Andres