Since their or two domain controller and where their or three active directory is associates.
When we query for DNS, end user need to see the positive reply from list of servers. Possible for scanning the IPV6 address across the domains and find as positive or negative response. End user has to decide the primary and secondary domain controller’s
Normally secondary domain controller’s as to be configured as standard alone. On success on deciding primary and secondary domain controller’s automate the process from primary to secondary by configuration with ns records. Possible for domain partition also.