I think this will depend greatly on your DataMiner version. For versions where Ticketing is not yet stored in Elastic (before 10.0.13.0 and 10.1.0.0) you can find the domain in C:\Skyline DataMiner\Ticketing\TicketFieldResolvers.json. You can open that file and copy the resolver (JSON serialized) and paste it in the same file on the target DMS. In theory after restarting it should be available. (Note I haven't tested this)

For a DataMiner running Ticketing with Elastic it will be harder to export this. You may be able to do something similar through Kibana, but I'm not familiar with how Elastic stores the domains.