AZ-305 Question #437: Real Exam Question with Answer & Explanation

Question

Hotspot Question You have an Azure subscription. You are designing a Microsoft SQL Server failover cluster instance (FCI) solution. The solution must meet the following requirements: - Ensure that the FCI contains three virtual machines that run Windows Server 2025. - Place the virtual machines and storage resources in three availability zones to provide an availability SLA of 99.99%. - Minimize read/write latency for storage without affecting the availability SLA of the virtual machines. - Ensure that neither a network load balancer nor a distributed network name (DNN) are required. - Minimize administrative effort. You need to recommend which type of storage to use and the minimum number of subnets required for the FCI. What should you recommend? To answer, select the appropriate options in the answer area. NOTE: Each correct selection is worth one point. Answer:

Options

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Explanation

This question tests knowledge of Azure SQL Server Failover Cluster Instance (FCI) design, specifically the appropriate storage type and subnet configuration to meet availability, latency, and simplicity requirements across three availability zones.

Approach. The correct storage type is Azure Shared Disk (Premium SSD or Ultra Disk) - specifically Azure Shared Ultra Disk, because it provides the lowest read/write latency among Azure shared storage options and supports zone-redundant configurations across three availability zones. Ultra Disk minimizes latency while maintaining the 99.99% SLA. For subnets, the minimum required is 1 subnet - when using Azure Shared Disk with Windows Server 2025 and a multi-subnet FCI configuration, you need at least 1 subnet per availability zone, making the minimum 3 subnets total; however, with the requirement that neither a network load balancer nor DNN is needed, a multi-subnet FCI (introduced in SQL Server 2019+) allows virtual machines in different subnets to register all IP addresses in DNS, eliminating the need for an NLB or DNN. The minimum number of subnets required is therefore 3 (one per availability zone). The combination of Azure Shared Ultra Disk + 3 subnets (multi-subnet FCI) satisfies all stated requirements: 99.99% SLA via zone distribution, minimal latency via Ultra Disk, no NLB/DNN via multi-subnet FCI, and minimal administrative effort.

Concept tested. Azure SQL Server FCI design across availability zones - specifically the use of Azure Shared Ultra Disk for low-latency shared storage, and the multi-subnet FCI topology (3 subnets across 3 availability zones) to eliminate the need for a network load balancer or DNN while maintaining the 99.99% availability SLA in Windows Server 2025 environments.

Reference. https://learn.microsoft.com/en-us/azure/azure-sql/virtual-machines/windows/failover-cluster-instance-azure-shared-disks-deploy?view=azuresql

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