nginx status code 200 and 304

Question

I'm using nginx + passenger. I'm trying to understand the nginx response 200 and 304. What does this both means? Sometimes, it responses back in 304 and others only 200. Reading the YUI blog , it seems browser needs the header "Last-Modified" to verify with the server. I'm wondering why the browser need to verify the last modified date. Here is my nginx configuration:

location / {
    root /var/www/placexpert/public;   # <--- be sure to point to 'public'!
    passenger_enabled on;
    rack_env development;
    passenger_use_global_queue on;

    if ($request_filename ~* ^.+\.(jpg|jpeg|gif|png|ico|css|js|swf)$) {
        expires max;
        break;
    }
}

How would I add the header "Last-Modified" to the static files? Which value should I set?

Answer 1

Try this.

if (...){
    expires max;
    add_header Last-Modified $sent_http_Expires;
    break;
}