Question: how to check additional domain controller is working or not?
Answer: Step 1 - Check the replication health. Run the following command : ...  Step 2 - Check the inbound replication requests that are queued. ...  Step 3 - Check the replication status. ...  Step 4 - Synchronize replication between replication partners. ...  Step 5 - Force the KCC to recalculate the topology. ...  Step 6 - Force replication.