I have two Domain controllers that I use for DNS as primary and secondary. I've defined these two servers as DNS in my DHCP scope in which users pick up DHCP/DNS settings from. We've just implemented OpenDNS Umbrella web filtering tool in our environment. To make the web filtering tool work, two Virtual appliances have been deployed. These two appliances route local DNS queuries and point to the cloud. I've now set these two Virtual appliances as DNS servers in my DHCP scope. There is redundancy to where if one appliance fails, the other appliance will stay up. However, my boss wants more redundancy. He wants me to create a GPO to where if and when both virtual appliances fail, a GPO will switch all users DNS settings back to my Domain controllers. it will be great if this GPO can refresh user's workstation or reboot them, so it will roll back to the DCs if both the Virtual appliances fail. By the way, these Virtual appliances are Linux base.