http://184.108.40.206.ipaddress.com/ may help you track down the app trying to open this site.
will tell you what apps are using what connections.
As to how to block an IP - it depends on what product you are using?
With the home product you can block an IP if you wish in the Firewall. Open SecurityCenter, click Web & Email Protection then Firewall, then My Network Connections and add it there and use the Blocked option in the drop-down menu.