http://manpages.ubuntu.com/manpages/yakkety/man8/sysctl.8.html

Don't forget to use --system if you need to take in to account settings that you have put in to /etc/sysctl.d.

From the manpage sysctl(8):

--system
    Load settings from all system configuration files.
    /run/sysctl.d/*.conf
    /etc/sysctl.d/*.conf
    /usr/local/lib/sysctl.d/*.conf
    /usr/lib/sysctl.d/*.conf
    /lib/sysctl.d/*.conf
    /etc/sysctl.conf