How To Verify That Nginx Fastcgi-Cache Is Working
Setting up fastcgi caching on your nginx webserver is a great idea. Especially if you are running a WordPress site or a site that otherwise uses a lot of server power to process each page. I won't go into how to configure fastcgi in this article. However, once things are setup, the best way to check if nginx is serving up cached content is to load a website on the server and look at the HTTP headers.
To do this in Firefox you first open the website on your nginx server. Then go to Tools, Web Developer, Network. You may have to reload the page to get any sort of data here. Click on the first html item, which will be the page itself and you should see the HTML headers. What you are looking for is something that reads
HIT means that fastcgi is working. MISS or anything else means that the page was not served from cache. You can try refreshing the page a few times to see if the cache needed to be created. But if after a few refreshes of the page you are still not seeing a HIT it means that fastcgi is not caching the page you are looking at.