You have an Azure subscription that contains two instances of SQL Server on Azure Virtual Machines named VM1 and VM2. Both instances run Microsoft SQL Server 2019 CU8. You need to deploy a failover cluster instance (FCI) to VM1 and VM2. The solution must eliminate the need for the following: • A distributed network name (DNN) • A load balancer What should you do?

To eliminate the need for an Azure Load Balancer or a Distributed Network Name (DNN) for a SQL Server Failover Cluster Instance (FCI), you must configure a multi-subnet cluster. By placing each virtual machine (VM1 and VM2) in a different subnet, the cluster's virtual network name (VNN) can be configured with an IP address in each subnet. Client applications that specify MultiSubnetFailover=True in their connection string will attempt to connect to all registered IP addresses for the VNN in parallel. The client driver connects to the first IP that responds, which will be the one on the active node's subnet. This client-side redirection capability natively handles failover without requiring a load balancer or DNN.

A. Proximity placement groups are used to reduce network latency between VMs by co-locating them. This does not affect the client connectivity method required for an FCI.
B. Using different proximity placement groups would increase network latency, which is detrimental to cluster performance, and does not address the client connectivity requirement.
C. A single-subnet configuration is the standard deployment that explicitly requires either an Azure Load Balancer or a DNN to route traffic to the active FCI node in Azure.

1. Microsoft Docs. (2023). Cluster on multiple subnets - SQL Server on Azure VMs. Azure SQL Documentation. Retrieved from https://learn.microsoft.com/en-us/azure/azure-sql/virtual-machines/windows/failover-cluster-instance-multi-subnet-group-configure.

Reference Point: The introduction states

"The multi-subnet approach provides an alternative for connectivity to your failover cluster instance (FCI) than the recommended Distributed Network Name (DNN) option." The "Prerequisites" section also recommends placing nodes in different subnets within the same virtual network.

2. Microsoft Docs. (2023). Failover cluster instances with SQL Server on Azure VMs. Azure SQL Documentation. Retrieved from https://learn.microsoft.com/en-us/azure/azure-sql/virtual-machines/windows/failover-cluster-instance-overview.

Reference Point: The "Connectivity" section discusses the challenges with the Virtual Network Name (VNN) in Azure on a single subnet

which necessitates either a Load Balancer or a DNN. This implicitly supports the multi-subnet approach as the alternative that avoids these components.