Hi,
To restore a configuration backup that contains the domain controller module within it, you must have the following:
1. The same hostname and domain are configured in System → General.
2. The DNS and Domain controller modules must be enabled (default values are OK).
Once both modules are up and running with the default information, you can import the configuration backup.
NOTE: If I were you, I would reinstall the server and then, repeat the mentioned process, just make sure the configuration backup is not deleted by accident.
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This world is ours, and by the Holy Light, we will keep it safe, now and forever.