very simple question about cache

[absolutely_free at libero.it]

Hi,I set simply reverse proxy (backend is an Apache web server):
upstream backend {        ip_hash;        server 127.0.0.1:8080; }

server {        listen x.y.w.z:80; # IP goes here.        server_name somedomain.com;        expires off;        location / {            proxy_pass http://backend;            }        real_ip_header X-Forwarded-For;
        # Set proxy headers for the passthrough        proxy_set_header Host $host;        proxy_set_header X-Real-IP $remote_addr;        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;                access_log /var/log/nginx/domain.cache.log cache;        access_log /var/log/nginx/domain.access.log;}


While browsing website, I see lots on entry in /var/log/nginx/domain.cache.log file (of course in /var/log/nginx/domain.access.log too).My question is: with this configuration, is there any caching active?

Example of cache log:
***05/Jul/2016:21:15:59 +0200 - Cache-Control: - Expires: - some.domain.net "GET /wp-admin/load-scripts.php?c=0&load%5B%5D=hoverIntent,common,admin-bar,wp-ajax-response,jquery-color,wp-lists,quicktags,jquery-query,admin-comments,jquery-ui-core,jquery-&load%5B%5D=ui-widget,jquery-ui-mouse,jquery-ui-sortable,postbox,dashboard,underscore,customize-base,customize-loader,thickbox,plugin-instal&load%5B%5D=l,shortcode,media-upload,svg-painter,heartbeat,wp-auth-check,wp-a11y,wplink,jquery-ui-position,jquery-ui-menu,jquery-ui-autocomp&load%5B%5D=lete&ver=4.5.3 HTTP/1.1" (304) "Mozilla/5.0 (Windows NT 10.0; WOW64; rv:47.0) Gecko/20100101 Firefox/47.0" Args: c=0&load%5B%5D=hoverIntent,common,admin-bar,wp-ajax-response,jquery-color,wp-lists,quicktags,jquery-query,admin-comments,jquery-ui-core,jquery-&load%5B%5D=ui-widget,jquery-ui-mouse,jquery-ui-sortable,postbox,dashboard,underscore,customize-base,customize-loader,thickbox,plugin-instal&load%5B%5D=l,shortcode,media-upload,svg-painter,heartbeat,wp-auth-check,wp-a11y,wplink,jquery-ui-position,jquery-ui-menu,jquery-ui-autocomp&load%5B%5D=lete&ver=4.5.3 Wordpress Auth Cookie:  ***05/Jul/2016:21:16:59 +0200 - Cache-Control: no-cache, must-revalidate, max-age=0 Expires: Wed, 11 Jan 1984 05:00:00 GMT some.domain.net "POST /wp-admin/admin-ajax.php HTTP/1.1" (200) "Mozilla/5.0 (Windows NT 10.0; WOW64; rv:47.0) Gecko/20100101 Firefox/47.0" Args: - Wordpress Auth Cookie:  ***05/Jul/2016:21:18:59 +0200 - Cache-Control: no-cache, must-revalidate, max-age=0 Expires: Wed, 11 Jan 1984 05:00:00 GMT some.domain.net "POST /wp-admin/admin-ajax.php HTTP/1.1" (200) "Mozilla/5.0 (Windows NT 10.0; WOW64; rv:47.0) Gecko/20100101 Firefox/47.0" Args: - Wordpress Auth Cookie: 

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