I have Samba 4 DC(DC1) and recently i added another DC2(Windows 2008 R2). I plan to demote DC1 and then add another Win DC. FSMO roles was transferred to DC2 server and DC2 works fine. Dcdiag and repadmin tests passed successfully.
At this moment DC2 configured to use DC1 DNS server as primary. I want to be sure that after i demote DC1 there will be no DNS errors so i set primary DNS of DC2 to its local DNS server. Everything still works, various tests passed against new primary DNS but after i reboot DC2 it seems can't locate anything related to domain at statup. The symptoms is long logon time and various dns related errors in logs such:
Name resolution for the name "_ldap._tcp.Default-First-Site-Name._sites.dc._msdcs.domain.local" timed out after none of the configured DNS servers responded.
Im 100% sure that its not firewall/connectivity problem because before reboot everything works fine. It seems netlogon doing queries before DNS service actually starts. I know that having two or more DC's is a requirement but is there any way to make single DC works as AD+DNS? At least temporarily.