How to backup and restore to Domain Controllers from an untrusted domain on the same network? (4247474)

How to backup and restore to Domain Controllers from an untrusted domain on the same network?

A below mentioned error message might also be displayed when the backup fails.

• Failed to connect to backup agent: Cannot establish the connection to the backup agent using TCP port 3843

1. On the RMAD server navigate to C:\Windows\System32\drivers\etc and open the HOSTS file in notepad
2. Add 2 lines to the file for each DC, one line with the IP Address and netbios name and one line with the IP Address and the FQDN. For example:
   IPAddress    Servername
   IPAddress    Servername.domainname
3. Create a new computer collection for the remote DCs
4. Add the DCs to the collection
5. Right click the collection and select Properties
6. Select the Agent Settings tab
7. Check Use the following account to access Backup Agent and backup files option and provide credentials that have rights to backup the remote DCs