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This is will be my first big project. We have 4 Replica Always on availability group with 3 Replica on site and another replica offsite (different subnet) the File share witness will be placed on site on the primary data center. On various online resources i saw that we need 2 Domain controllers one onsite and the other one on the Disaster Recovery site. My question is what will be the problems that i will face if all the replicas are joined to one Domain controller .

Suppose if the Primary site goes down the server on the DR will still be able to used cached credentials.

The distance between Primary and Disaster Recovery site only 20 Miles !

Any advice on this will be highly appreciated.

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Suppose if the Primary site goes down the server on the DR will still be able to used cached credentials.

Assuming the DCs and the rest of your infrastructure will fail over to DR by some other means, your DR SQL Server may not be usable until that happens. So the AG will give you a very good Recovery Point Objective (RPO), but the Recovery Time Objective (RTO) won't be any better than a VM failover.

  • My network admin told me even i start the cluster services on the DR without a quorum the clients cannot connect if the whole primary site goes down. – SQL_NoExpert Dec 24 '18 at 0:57
  • Can you please briefly explain what is the benefit of having a second Domain controller – SQL_NoExpert Dec 24 '18 at 0:58
  • As your admin said, clients would be able to authenticate to and connect to SQL Server. Without a working DC clients using domain accounts won't be able to authenticate. – David Browne - Microsoft Dec 24 '18 at 13:11
  • Thanks for the information. If I need to have a second Domain Controller on the Disaster Recovery site is there anything i need to do from a DBA point of view or I can simply tell my network admin to provide a Domain controller at the DR site. – SQL_NoExpert Dec 24 '18 at 14:03

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