Our ADI Sync Tool is written in C#, which uses environment variables to access proxy information. This means you must first add the appropriate HTTPS_PROXY variable before you can use Active Directory through a proxy. 

Follow the steps below to add the necessary environment variable:

1. From your system’s Control Panel, right-click This PC.
2. From the drop-down menu that opens, select Properties.
3. From the screen that opens, click on Change settings.
4. In the window that opens, click on the Advanced tab. 
5. Click on Environment Variables at the bottom of the window.
6. Under System Variables, click New.
7. Add a system variable named HTTPS_PROXY and set the value to specify your IP address and port number in the following format: http://[IPaddress:port] For example: http://10.1.20.102:3128/
   
   Note: If your proxy server requires a username and password, include the credentials in this syntax: https_proxy = http://username:password@proxy.example.com:8080
8. Click OK.

For more information, see this article from Cloud Foundry.