High availability design patterns in Azure - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create an Azure Load Balancer resource.

Azure

resource "azurerm_lb" "example" {
  name                = "example-lb"
  location            = azurerm_resource_group.example.location
  resource_group_name = azurerm_resource_group.example.name
  sku                 = "[1]"
}

Drag options to blanks, or click blank then click option'

AStandard

BBasic

CPremium

DFree

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing Basic SKU which lacks zone redundancy.

Using Premium SKU which is not valid for Load Balancer.

Selecting Free which does not exist.

The Standard SKU is recommended for high availability because it supports zone redundancy and better performance.

2fill in blank

medium

Complete the code to define an availability set with fault domains.

Azure

resource "azurerm_availability_set" "example" {
  name                         = "example-avset"
  location                     = azurerm_resource_group.example.location
  resource_group_name          = azurerm_resource_group.example.name
  platform_fault_domain_count  = [1]
  platform_update_domain_count = 5
}

Drag options to blanks, or click blank then click option'

A3

B2

C1

D4

Attempts:

3 left

💡 Hint

Common Mistakes

Using 1 fault domain which offers no redundancy.

Using 4 which is not supported in some regions.

Confusing fault domains with update domains.

Setting platform_fault_domain_count to 3 distributes VMs across three fault domains for high availability.

3fill in blank

hard

Fix the error in the Azure Traffic Manager profile configuration.

Azure

resource "azurerm_traffic_manager_profile" "example" {
  name                = "example-tm"
  resource_group_name = azurerm_resource_group.example.name
  location            = "global"
  profile_status      = "Enabled"
  traffic_routing_method = "[1]"
  dns_config {
    relative_name = "exampletm"
    ttl           = 30
  }
}

Drag options to blanks, or click blank then click option'

ARoundRobin

BWeighted

CPerformance

DPriority

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect casing like 'weighted'.

Using unsupported routing methods.

Confusing routing method with profile status.

The correct traffic routing method is Weighted (case-sensitive) to distribute traffic evenly.

4fill in blank

hard

Fill both blanks to configure a virtual machine scale set with automatic upgrade policy.

Azure

resource "azurerm_linux_virtual_machine_scale_set" "example" {
  name                = "example-vmss"
  location            = azurerm_resource_group.example.location
  resource_group_name = azurerm_resource_group.example.name

  upgrade_policy_mode = "[1]"

  automatic_os_upgrade_policy {
    enable_auto_os_upgrade = [2]
  }
}

Drag options to blanks, or click blank then click option'

AManual

BAutomatic

Ctrue

Dfalse

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'Manual' disables automatic upgrades.

Setting enable_auto_os_upgrade to false disables upgrades.

Using uppercase True or False causes errors.

Setting upgrade_policy_mode to Automatic enables automatic upgrades, and enable_auto_os_upgrade must be true to activate it.

5fill in blank

hard

Fill all three blanks to define a health probe and backend pool for an Azure Application Gateway.

Azure

resource "azurerm_application_gateway" "example" {
  name                = "example-appgw"
  location            = azurerm_resource_group.example.location
  resource_group_name = azurerm_resource_group.example.name

  backend_address_pool {
    name = "[1]"
  }

  probe {
    name                = "[2]"
    protocol            = "[3]"
    host                = "localhost"
    path                = "/health"
    interval            = 30
    timeout             = 30
    unhealthy_threshold = 3
  }
}

Drag options to blanks, or click blank then click option'

AbackendPool1

BhealthProbe1

CHttp

DHttps

Attempts:

3 left

💡 Hint

Common Mistakes

Using inconsistent names between backend pool and probe.

Setting protocol to 'Https' without proper certificates.

Leaving probe name empty.

The backend pool is named backendPool1, the probe is named healthProbe1, and the protocol is Http for health checks.

Practice

1. Which Azure service is primarily used to distribute incoming traffic across multiple virtual machines to ensure high availability?

easy

A. Azure Functions

B. Azure Blob Storage

C. Azure Load Balancer

D. Azure Cosmos DB

Solution

1. Step 1: Understand the role of Azure Load Balancer

   Azure Load Balancer distributes incoming network traffic across multiple VMs to prevent any single VM from becoming a bottleneck.

2. Step 2: Compare with other services

   Azure Blob Storage stores data, Azure Functions run code, and Cosmos DB is a database service; none distribute traffic.

3. Final Answer:

   Azure Load Balancer -> Option C

4. Quick Check:

   Traffic distribution = Azure Load Balancer [OK]

Hint: Load Balancer spreads traffic to VMs for uptime [OK]

Common Mistakes:

• Confusing storage or compute services with traffic distribution
• Choosing Azure Functions for load balancing
• Selecting database services for availability patterns

2. Which of the following is the correct syntax to create an Azure VM Scale Set using Azure CLI for high availability?

easy

A. az vm create --name MyScaleSet --resource-group MyResourceGroup --image UbuntuLTS --instance-count 3

B. az vm create --name MyScaleSet --resource-group MyResourceGroup --image UbuntuLTS --count 3

C. az vmss deploy --name MyScaleSet --group MyResourceGroup --image UbuntuLTS --instances 3

D. az vmss create --name MyScaleSet --resource-group MyResourceGroup --image UbuntuLTS --instance-count 3

Solution

1. Step 1: Identify the correct Azure CLI command for VM Scale Set creation

   The command to create a VM Scale Set is az vmss create, not az vm create.

2. Step 2: Check the parameters

   Parameters like --name, --resource-group, --image, and --instance-count are correctly used in az vmss create --name MyScaleSet --resource-group MyResourceGroup --image UbuntuLTS --instance-count 3.

3. Final Answer:

   az vmss create --name MyScaleSet --resource-group MyResourceGroup --image UbuntuLTS --instance-count 3 -> Option D

4. Quick Check:

   VM Scale Set creation uses az vmss create [OK]

Hint: Use 'az vmss create' for VM Scale Sets [OK]

Common Mistakes:

• Using 'az vm create' instead of 'az vmss create'
• Incorrect parameter names like --count instead of --instance-count
• Mixing resource group parameter names

3. Consider this Azure Load Balancer configuration snippet:

frontendIPConfiguration:
  name: LoadBalancerFrontEnd
  publicIPAddress:
    id: /subscriptions/xxx/resourceGroups/rg/providers/Microsoft.Network/publicIPAddresses/myPublicIP
backendAddressPools:
  - name: BackendPool
loadBalancingRules:
  - name: HTTPRule
    frontendIPConfiguration: LoadBalancerFrontEnd
    backendAddressPool: BackendPool
    protocol: Tcp
    frontendPort: 80
    backendPort: 80
    enableFloatingIP: false
    idleTimeoutInMinutes: 4
    loadDistribution: Default

What will happen if one VM in the backend pool becomes unhealthy?

medium

A. Traffic will automatically stop going to the unhealthy VM

B. Traffic will continue to be sent to the unhealthy VM

C. Load Balancer will restart the unhealthy VM

D. Load Balancer will redirect traffic to a different port

Solution

1. Step 1: Understand Azure Load Balancer health probe behavior

   Azure Load Balancer requires health probes configured to detect unhealthy VMs and stop sending traffic to them. This snippet does not show health probes configured, but in practice, health probes are necessary for proper load balancing.

2. Step 2: Analyze the effect of missing health probes

   Without health probes, the Load Balancer cannot detect unhealthy VMs, so it continues sending traffic to all VMs in the backend pool. However, best practice is to configure health probes to avoid this.

3. Final Answer:

   Traffic will automatically stop going to the unhealthy VM -> Option A

4. Quick Check:

   Health probes detect unhealthy VMs and stop traffic [OK]

Hint: Configure health probes to avoid sending traffic to bad VMs [OK]

Common Mistakes:

• Assuming Load Balancer auto-detects unhealthy VMs without probes
• Thinking Load Balancer restarts VMs
• Confusing port redirection with load balancing

4. You have configured an Active-Passive high availability setup using Azure Traffic Manager. However, during failover, users experience downtime. What is the most likely cause?

medium

A. Traffic Manager is set to Performance routing with multiple active endpoints

B. Traffic Manager is set to Priority routing but health probes are misconfigured

C. Azure Load Balancer is not configured with a public IP

D. VM Scale Set has only one instance

Solution

1. Step 1: Understand Active-Passive with Traffic Manager Priority routing

   Priority routing sends traffic to the primary endpoint unless it is unhealthy, then fails over to secondary.

2. Step 2: Identify impact of misconfigured health probes

   If health probes are misconfigured, Traffic Manager cannot detect endpoint health and will not failover properly, causing downtime.

3. Final Answer:

   Traffic Manager is set to Priority routing but health probes are misconfigured -> Option B

4. Quick Check:

   Priority routing + bad probes = failover fails [OK]

Hint: Check health probes when failover fails in Priority routing [OK]

Common Mistakes:

• Confusing routing methods in Traffic Manager
• Blaming Load Balancer or VM Scale Set for Traffic Manager failover
• Ignoring health probe configuration

5. You want to design a geo-redundant high availability solution for a web app in Azure that must remain available even if an entire Azure region fails. Which combination of Azure services and design patterns best achieves this?

hard

A. Deploy the app in two regions with Azure Traffic Manager using Performance routing and Azure SQL Geo-Replication

B. Deploy the app in one region with Azure Load Balancer and VM Scale Sets, and use Azure Backup for disaster recovery

C. Deploy the app in two regions with Azure Traffic Manager using Priority routing and VM Scale Sets in each region

D. Deploy the app in one region with Azure Application Gateway and use Azure Blob Storage for static content

Solution

1. Step 1: Understand geo-redundancy requirements

   To survive a full region failure, the app must be deployed in multiple regions with traffic routed between them.

2. Step 2: Evaluate options for traffic routing and data replication

   Performance routing in Traffic Manager directs users to the closest healthy region. Azure SQL Geo-Replication ensures database availability across regions.

3. Step 3: Compare with other options

   Priority routing is for Active-Passive, not best for geo-load balancing. Single region deployments cannot survive region failure. Application Gateway is regional and does not provide geo-failover.

4. Final Answer:

   Deploy the app in two regions with Azure Traffic Manager using Performance routing and Azure SQL Geo-Replication -> Option A

5. Quick Check:

   Geo-redundancy needs multi-region + performance routing + geo-replication [OK]

Hint: Use multi-region + Traffic Manager Performance + Geo-Replication [OK]

Common Mistakes:

• Choosing Priority routing for geo-load balancing
• Relying on single region with backup for high availability
• Confusing Application Gateway with global traffic routing