How to tell nginx to honor backend's cache?

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http://serverfault.com – I'm using php-fpm with nginx as http server (I don't know much about reverse proxies, I just installed it and didn't touch anything), without Apache nor Varnish. I need nginx to understand and honor the http headers I send. I tried with this config (taken from the docs) but didn't work: /etc/nginx/nginx.conf: fastcgi_cache_path /var/lib/nginx/cache levels=1:2 keys_zone=website:10m inactive=10m; fastcgi_cache_key "$scheme$request_method$host$request_uri"; /etc/nginx/sites-available/website: server { fastcgi_cache website; #fastcgi_cache_valid 200 302 1h; #fastcgi_cache_valid 3 (HowTos)