If no preferred_domain_controller is specified, we follow the usual discovery process (LDAP-PING and DNS lookup) to get the list of Site local DC.
However, if preferred_domain_controller is specified, we no longer do a DNS lookup and use preferred_domain_controller instead. if it is not reachable, then the domain join operation will fail. Always have a choice to fall back to default domain join process where no preferred_domain_controller is specified.
If we look at Domain Join iDC discovery workflow {Default}] in log file - ~/data/logs/minerva_cvm.log |
Domain Join opreferred_domain_controller]
After learning and feedback from Vodafone account, we made certain changes to the Configure NameServices Task. So now we no longer reply on Site local DC list returned by DNS query, instead preferred_domain_controller is used.
Before 3.1 and 2.2.3 even if a preferred DC is specified and it's not reachable due to some reason, we used to fall back to normal discovery by doing a DNS lookup and LDAP-PING to all DC's in the received order in the Default-First-Site.