Hi, I have AD domain controllers running samba 4.2 turnkey linux (domain controller). Well I am trying to evaluate the failover while Primary AD is down and backup take position and serve to the client's request. dc1.linuxad.org dc2.inuxad.org If my Primary AD(dc1) is down, my "Active Directory Users and Computers" management console failed to retrieve objects. I couldn't see any of the DC in the list.error is https://i.stack.imgur.com/uKdhz.png I couldn't change the password through windows while the DC is down. my DNS address is pointed to dc2 IP address, but still error. https://i.stack.imgur.com/aXogj.png These are my steps I have done, 1. Transferred the Infrastructure Master role to dc2 for replication take place in time. 2. according to Microsoft AD, Infrastructure Master role should not accompany with GC server, the dc2 is became GC while enrolling as domain controller. my queries are: 1. the above two points are actually exemplify the Microsoft AD term in this Samba AD services? 2. what is the purpose of backup AD here, which is not serving while primary is down? Are these issues because of the samba version which I am using ?