Each aspect of the Countermark system requires the following domain to be accessible:

countermark.com

This includes the phone Countermark app as well as desktop computers.
The Countermark website is routinely tested on the most popular browser and computer combinations.

We recommended using the Google Chrome browser with cookies enabled for best performance.

To install the Countermark Word Add-in, the following domains need to be allowed through your firewall:

microsoft.com
microsoftonline.com
office.com
office.net

In addition to those listed above, running the Countermark Word Add-in also requires the following to be allowed through your firewall:

aspnetcdn.com
azurewebsites.net
bootstrapcdn.com