Merge pull request #1858 from suresh-kandoth/patch-5

add FCI requirements for domain joined cluster

Author: Jak-MS

docs/sql-server/failover-clusters/install/before-installing-failover-clustering.md

@@ -140,6 +140,12 @@ manager: craigg
 -   Review content in [Security Considerations for a SQL Server Installation](../../../sql-server/install/security-considerations-for-a-sql-server-installation.md).  
 
 -   To enable Kerberos authentication with [!INCLUDE[ssNoVersion](../../../includes/ssnoversion-md.md)], see [How to use Kerberos authentication in SQL Server](https://support.microsoft.com/kb/319723) in the [!INCLUDE[msCoName](../../../includes/msconame-md.md)] Knowledge Base.  
+
+-   SQL Server failover cluster instance (FCI) requires the cluster nodes to be domain joined. The following configurations are **not supported**: 
+    *	SQL FCI on workgroup clusters. 
+    *	SQL FCI on Multi-Domain cluster.   
+    *	SQL FCI on Domain + Workgroup Clusters. 
+
 
 ##  <a name="Network"></a> Review Network, Port, and Firewall Considerations