This chapter covers Azure Dedicated Hosts, a service that provides physical servers dedicated to your workloads, giving you control over maintenance, placement, and isolation. For AZ-900, this topic appears under Objective 2.2 (Describe Azure compute and networking services) and is typically tested with 1-2 questions focusing on use cases, benefits over shared infrastructure, and licensing scenarios. Understanding Dedicated Hosts helps you answer questions about compliance, licensing (like Windows Server or SQL Server), and situations requiring physical isolation.
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Imagine you run a busy delivery company and you lease trucks from a fleet service. Normally, you share the fleet — any truck might be assigned to you on any day, and you don't know which specific truck you'll get. This works fine for most deliveries, but some of your drivers have special equipment or need exact configurations (like a refrigerated compartment). One day, a driver reports that a truck smells like fish from a previous load, ruining your perishable goods. You realize you need dedicated trucks — reserved exclusively for your company, parked in a specific spot, and never used by anyone else. In Azure, a Dedicated Host is like reserving that entire physical server for your VMs. You get the whole host to yourself — no other customer's VMs run on it. You control maintenance timing, you can see the exact hardware, and you can place your VMs exactly where you want. The cost is higher because you pay for the entire host, not just the VMs you use. It's the difference between renting a shared office floor (you get space but not specific desks) and leasing the entire building (you control everything). Azure's Dedicated Hosts give you that exclusive, physical isolation for compliance, licensing, and performance predictability.
What is Azure Dedicated Host?
Azure Dedicated Host is a service that provides a physical server (host) dedicated to your Azure subscription. Unlike regular VMs that run on shared hardware where multiple customers' VMs may coexist on the same physical server, a Dedicated Host ensures that the entire physical machine is reserved for your use only. This addresses several business problems:
Compliance and security: Some regulatory standards (e.g., HIPAA, PCI DSS, or government certifications) require that data processing occurs on hardware not shared with other organizations. Dedicated Hosts provide physical isolation at the hardware level.
Licensing: Many software licenses, especially for Windows Server and SQL Server, are tied to physical cores. With shared infrastructure, you cannot guarantee which physical cores your VM uses, making license compliance difficult. Dedicated Hosts allow you to see and control the physical cores, enabling you to apply existing licenses with Software Assurance or Azure Hybrid Benefit.
Performance predictability: When VMs share a physical host, resource contention (CPU, memory, I/O) can occur. Dedicated Hosts eliminate the "noisy neighbor" problem because no other customer's VMs run on that host.
Maintenance control: Azure periodically performs maintenance on physical hosts (e.g., firmware updates, hardware replacements). With Dedicated Hosts, you can control the timing of maintenance through a feature called Maintenance Control, allowing you to schedule updates during your maintenance windows.
How It Works – Step by Step
Provision a Dedicated Host: You create a Dedicated Host resource in an Azure region and availability zone. You select a host SKU that defines the underlying hardware (e.g., Intel Xeon or AMD EPYC processors), number of physical cores, and amount of physical RAM. The host SKU also determines which VM sizes can be deployed on it. For example, the Dsv3-Type1 host supports Dsv3-series VMs.
Create a Host Group: Optionally, you can group Dedicated Hosts into a host group for high availability. A host group can contain up to 10 hosts, and you can deploy VMs across them to meet availability requirements (similar to availability sets but at the physical host level).
Deploy VMs onto the Host: When you create a VM, you specify the Dedicated Host (or host group) where it should run. The VM is then placed onto that specific physical server. You cannot migrate a VM from one Dedicated Host to another without stopping it first (unless using host group with automatic placement).
Manage the Host: You can view the host's health, resource usage (CPU, memory), and maintenance status. You can also enable Maintenance Control to schedule host updates. The host is billed per hour, regardless of how many VMs are running on it.
Key Components and Pricing
Host SKUs: Each SKU specifies the processor family, number of physical cores, and supported VM series. For example:
- Dsv3-Type1: Intel Xeon E5-2673 v4, 24 cores, 224 GB RAM - Esv3-Type1: Intel Xeon E5-2673 v4, 24 cores, 448 GB RAM - Fsv2-Type2: Intel Xeon Platinum 8168, 36 cores, 144 GB RAM - Pricing: You pay for the entire Dedicated Host per hour. The price varies by SKU and region. For example, a Dsv3-Type1 host might cost around $3.50/hour in the US East region. This is significantly more expensive than running the same number of VMs on shared infrastructure, but it provides isolation and licensing benefits. - Azure Hybrid Benefit: You can apply your existing Windows Server or SQL Server licenses with Software Assurance to reduce the cost of the VM instances running on Dedicated Hosts. This is a key reason customers choose Dedicated Hosts.
Comparison to On-Premises Equivalent
Running workloads on-premises requires purchasing, housing, powering, cooling, and maintaining physical servers. With Azure Dedicated Hosts, you still get a physical server, but Azure handles the physical maintenance (power, cooling, hardware repairs). You retain control over maintenance timing and VM placement, but you don't own the hardware. The cost model shifts from capital expenditure (buying servers) to operational expenditure (paying per hour).
Azure Portal and CLI Touchpoints
Portal: Navigate to "Dedicated Hosts" under Compute. Create a host, specify SKU, region, availability zone, and fault domain count. Then create VMs and assign them to the host.
CLI: Use the following commands to create a Dedicated Host and deploy a VM:
# Create a resource group
az group create --name MyResourceGroup --location eastus
# Create a Dedicated Host group
az vm host group create --name MyHostGroup --resource-group MyResourceGroup --location eastus --platform-fault-domain-count 1
# Create a Dedicated Host
az vm host create --name MyHost --resource-group MyResourceGroup --host-group MyHostGroup --sku DSv3-Type1 --location eastus
# Create a VM on the Dedicated Host
az vm create --name MyVM --resource-group MyResourceGroup --image UbuntuLTS --size Standard_D2s_v3 --host MyHost --host-group MyHostGroup --admin-username azureuser --generate-ssh-keysUse Cases
Regulatory compliance: Healthcare, finance, and government customers that require physical isolation.
License management: Organizations with existing Windows Server or SQL Server licenses that want to use Azure Hybrid Benefit.
Performance-sensitive workloads: Applications that cannot tolerate resource contention, such as real-time databases or high-performance computing.
SAP HANA: Large SAP HANA deployments often require dedicated hosts for performance and licensing reasons.
Limitations
Cost: Dedicated Hosts are expensive. You pay for the whole host even if you run only a few small VMs.
VM size constraints: Only specific VM sizes are supported per host SKU. You cannot mix different VM series on the same host.
Limited availability: Not all VM series are available as Dedicated Hosts, and availability varies by region.
No live migration: You cannot move a running VM to a different Dedicated Host without stopping it (except via host group automatic placement during maintenance).
Assess licensing and compliance needs
Before provisioning a Dedicated Host, identify whether your workloads require physical isolation due to compliance (e.g., HIPAA, PCI DSS) or licensing (e.g., Windows Server, SQL Server with Software Assurance). Determine the VM series and sizes you plan to run, as the host SKU must match. For example, if you need Dv3-series VMs, select a host SKU like Dsv3-Type1. Also consider the number of VMs and their resource requirements to ensure a single host has enough physical cores and RAM.
Create a host group for high availability
If you need high availability across physical hosts, create a host group. Specify the number of fault domains (up to 3) to spread VMs across different physical racks. A host group can contain up to 10 Dedicated Hosts. This step is optional but recommended for production workloads. In the Azure portal, go to 'Dedicated Hosts' > 'Host Groups' and create a new group with a name, region, and fault domain count. CLI: `az vm host group create`.
Provision the Dedicated Host
Create the Dedicated Host resource inside the host group (or standalone). Choose a host SKU that supports your desired VM sizes. For example, select 'DSv3-Type1' for Dsv3-series VMs. Specify the availability zone if needed. The host is billed per hour regardless of VM count. In the portal, click 'Add' under Dedicated Hosts, fill in the details, and create. CLI: `az vm host create`.
Deploy VMs onto the Dedicated Host
When creating a new VM, under the 'Advanced' tab, select 'Dedicated Host' and choose the host or host group. The VM will be placed on that specific physical server. You can also assign existing VMs to a host, but they must be stopped first. For example, create a Standard_D2s_v3 VM and assign it to the host. CLI: `az vm create --host ...`.
Configure maintenance control (optional)
To control when Azure performs maintenance on the physical host, enable Maintenance Control. This allows you to schedule host updates (e.g., firmware updates) during your maintenance windows. Create a maintenance configuration resource, assign it to the Dedicated Host, and set a schedule. Without this, Azure may perform maintenance at any time, potentially disrupting workloads.
Scenario 1: Healthcare Compliance
A hospital chain must process patient health records in the cloud while complying with HIPAA. They choose Azure Dedicated Hosts to ensure that no other customer's VMs share the same physical hardware. The IT team provisions a Dedicated Host in a US region, selects a host SKU that supports their Dv3-series VMs, and deploys their electronic health record (EHR) system. They also enable Maintenance Control to schedule updates during off-peak hours. Cost is higher — the host costs ~$3.50/hour, but the hospital avoids expensive compliance penalties. If they had used shared infrastructure, an auditor could argue that physical isolation is not guaranteed, potentially leading to non-compliance.
Scenario 2: SQL Server License Optimization
A financial services firm owns SQL Server Enterprise licenses with Software Assurance. They want to migrate their SQL Server workloads to Azure but need to prove license compliance. They provision a Dedicated Host with an Esv3-Type1 SKU (Intel Xeon, 24 cores). They deploy VMs using Azure Hybrid Benefit, which reduces the VM compute cost by up to 40%. The host is fully utilized with 4 VMs each using 6 cores. The firm pays for the host plus the reduced VM rates. If they had used shared infrastructure, they could not guarantee that the physical cores used by their VMs are dedicated, risking license violation.
Scenario 3: Noisy Neighbor Elimination
An e-commerce company runs a latency-sensitive database for real-time inventory. During peak sales, they noticed performance degradation due to resource contention on shared hosts. They migrate the database to a Dedicated Host with an Fsv2-Type2 SKU (high-frequency Intel Xeon). The host is dedicated to a single large VM (Standard_F72s_v2) that uses all 36 cores. Performance becomes predictable, and latency drops. However, the cost is high — the host costs ~$4.50/hour. The company accepts this because lost sales during slow periods cost more. A common mistake is not sizing the host correctly: if they had chosen a host with fewer cores, they might not have enough capacity for peak loads.
Objective 2.2: Describe Azure compute and networking services
AZ-900 tests your understanding of Dedicated Hosts primarily through scenario-based questions. You need to know: - What problem it solves: Physical isolation for compliance, licensing (Windows Server/SQL Server with Software Assurance), and eliminating noisy neighbors. - How it differs from shared infrastructure: Dedicated Hosts provide a physical server exclusively for your subscription; shared infrastructure hosts multiple customers' VMs on the same physical hardware. - When to choose Dedicated Hosts over other options: Use Dedicated Hosts when you need physical isolation, have existing licenses with Software Assurance, or require maintenance control. Do not choose Dedicated Hosts for cost savings — they are more expensive.
Common Wrong Answers and Why Candidates Choose Them
"Dedicated Hosts provide virtual isolation similar to a virtual network." This is wrong because virtual networks (VNets) provide network-level isolation, not physical hardware isolation. Candidates confuse the term 'dedicated' with 'virtual network isolation'.
"Dedicated Hosts are cheaper than regular VMs because you only pay for the VMs you use." This is false. You pay for the entire host per hour, even if you run only one small VM. Candidates mistakenly think 'dedicated' implies efficiency.
"Dedicated Hosts are the same as Azure Dedicated Virtual Machines." There is no such thing as 'Azure Dedicated Virtual Machines.' The exam may present this as a distractor. Dedicated Hosts are physical servers; isolated VMs (without dedicated hardware) are not a service.
"You can use Dedicated Hosts to run any VM size from any series." Wrong. Each host SKU supports only specific VM series and sizes. Candidates assume flexibility.
Specific Terms and Values
Host SKU: e.g., Dsv3-Type1, Esv3-Type1, Fsv2-Type2
Host group: Up to 10 hosts, up to 3 fault domains
Maintenance Control: Allows scheduling of host maintenance
Azure Hybrid Benefit: Reduces VM cost on Dedicated Hosts for Windows Server/SQL Server
Edge Cases and Tricky Distinctions
Dedicated Host vs. Single Tenant: Azure is a multi-tenant environment by default. Dedicated Hosts provide single-tenant physical servers. Single-tenant does not mean the host is dedicated to a single VM — you can run multiple VMs on the same host.
Dedicated Host vs. Reserved Instances: Reserved Instances provide a discount on VM costs but do not provide physical isolation. Candidates might confuse the two.
Dedicated Hosts and Availability Zones: You can deploy Dedicated Hosts in an availability zone for resilience, but you cannot use availability sets within a single host (you use host groups with fault domains instead).
Memory Trick
Think of the acronym LICENSE: - Licensing (Azure Hybrid Benefit) - Isolation (physical compliance) - Control (maintenance scheduling) - Eliminate noisy neighbors - Specific host SKUs (not all VM sizes) - Expensive (pay for whole host)
When you see a question about physical isolation or license compliance, choose Dedicated Hosts.
Azure Dedicated Host provides a physical server dedicated to your Azure subscription, ensuring hardware isolation.
Use Dedicated Hosts for compliance requirements (HIPAA, PCI DSS) that mandate physical separation.
Dedicated Hosts enable you to apply existing Windows Server or SQL Server licenses with Software Assurance via Azure Hybrid Benefit.
You pay for the entire host per hour, regardless of how many VMs are running; it is more expensive than shared infrastructure.
Each host SKU supports only specific VM series and sizes (e.g., Dsv3-Type1 supports Dsv3-series VMs).
You can control host maintenance timing using Maintenance Control.
Host groups allow up to 10 Dedicated Hosts and up to 3 fault domains for high availability.
Dedicated Hosts are not the same as isolated VMs; they provide physical isolation, not virtual network isolation.
These come up on the exam all the time. Here's how to tell them apart.
Azure Dedicated Host
Physical server dedicated to your subscription
Pay for the entire host per hour (higher cost)
Supports Azure Hybrid Benefit for licensing
Maintenance control available
Limited to specific VM series/sizes per host SKU
Regular Azure VM (Shared Infrastructure)
Physical server shared with other customers
Pay per VM per hour (lower cost)
Azure Hybrid Benefit available but license compliance harder to prove
No control over host maintenance timing
Wide range of VM sizes available
Mistake
Dedicated Hosts are the same as dedicated VMs (isolated VMs without sharing).
Correct
There is no 'dedicated VM' service in Azure. Dedicated Hosts provide a physical server dedicated to your subscription. VMs on a Dedicated Host still run on shared hypervisor but the physical hardware is not shared with other customers.
Mistake
You can use any VM size on any Dedicated Host SKU.
Correct
Each host SKU supports only specific VM series and sizes. For example, a Dsv3-Type1 host only supports Dsv3-series VMs. You cannot deploy a B-series VM on that host.
Mistake
Dedicated Hosts are cheaper than regular VMs because you only pay for the VMs you use.
Correct
You pay for the entire Dedicated Host per hour, regardless of how many VMs are running. This is almost always more expensive than running the same number of VMs on shared infrastructure.
Mistake
Dedicated Hosts eliminate all Azure maintenance downtime.
Correct
Dedicated Hosts still require maintenance (e.g., firmware updates). However, you can control the timing using Maintenance Control. Without it, Azure may perform maintenance at any time.
Mistake
You can live migrate VMs between Dedicated Hosts without downtime.
Correct
You cannot live migrate VMs between Dedicated Hosts. The VM must be stopped and restarted on the new host. However, host groups can automatically place VMs on another host during maintenance if configured.
A regular VM runs on shared physical hardware that may host VMs from other customers. A Dedicated Host reserves an entire physical server exclusively for your subscription. This provides physical isolation, licensing benefits, and maintenance control. However, Dedicated Hosts are significantly more expensive because you pay for the whole host, not just the VMs you use.
Use Dedicated Hosts when you need physical isolation for compliance (e.g., HIPAA, PCI DSS), when you have existing Windows Server or SQL Server licenses with Software Assurance that you want to apply via Azure Hybrid Benefit, or when you need to eliminate noisy neighbor performance issues. Do not use Dedicated Hosts for cost savings — they are more expensive than shared VMs.
No. Each Dedicated Host SKU supports only specific VM series and sizes. For example, a Dsv3-Type1 host supports Dsv3-series VMs (Standard_D2s_v3, Standard_D4s_v3, etc.). You must select a host SKU that matches your desired VM family. Check Azure documentation for supported sizes per SKU.
You are billed per hour for the entire Dedicated Host, regardless of how many VMs are running on it. The price depends on the host SKU and region. For example, a Dsv3-Type1 host costs approximately $3.50/hour in US East. You also pay for the VMs themselves, but you can reduce VM costs using Azure Hybrid Benefit if you have eligible licenses.
Yes, you can use Maintenance Control to schedule host maintenance (e.g., firmware updates) during your preferred windows. Without Maintenance Control, Azure may perform maintenance at any time, which could disrupt your workloads. Maintenance Control is an optional feature that requires creating a maintenance configuration and assigning it to the host.
A host group is a logical grouping of up to 10 Dedicated Hosts. You can specify up to 3 fault domains to spread VMs across different physical racks for high availability. When you create VMs in a host group, Azure automatically places them on available hosts within the group. This is similar to an availability set but at the physical host level.
Yes. Azure Hybrid Benefit allows you to use your existing Windows Server or SQL Server licenses with Software Assurance on Azure. When applied to VMs running on Dedicated Hosts, you pay a reduced rate for the VM compute (base compute rate minus license cost). This is a key reason customers choose Dedicated Hosts for licensing compliance.
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