So it says this on the docs : http://nginx.org/en/docs/http/ngx_http_proxy_module.html#proxy_cache_valid

The “X-Accel-Expires” header field sets caching time of a response in seconds. The zero value disables caching for a response. If the value starts with the @ prefix, it sets an absolute time in seconds since Epoch, up to which the response may be cached.

Can someone give an example of how this should look and what if i set it as zero what is the outcome then...?

//unknown outcome / result...?
X-Accel-Expires: @0

//Expire cache straight away.
X-Accel-Expires: 0

//Expire cache in 5 seconds
X-Accel-Expires: 5

//Expire cache in 5 seconds and allow "STALE" cache responses to be stored for 5 seconds ?????
X-Accel-expires: @5 5

Hopefully I am right thinking that the above would work like this need some clarification.

http://www.networkflare.com/