Why load balancing matters in Azure - See It in Action

Why Load Balancing Matters

📖 Scenario: You are managing a website hosted on Azure. Many users visit the site at the same time. To keep the website fast and reliable, you need to spread the work evenly across several servers.

🎯 Goal: Build a simple Azure load balancer configuration that distributes traffic to two virtual machines. This will help the website handle many visitors without slowing down or crashing.

📋 What You'll Learn

Create a resource group named MyResourceGroup

Create two virtual machines named VM1 and VM2

Create a load balancer named MyLoadBalancer that balances traffic between VM1 and VM2

Configure a backend address pool with VM1 and VM2

Set up a load balancing rule for HTTP traffic on port 80

💡 Why This Matters

🌍 Real World

Load balancing helps websites and apps stay fast and reliable when many users visit at the same time.

💼 Career

Cloud engineers and system administrators use load balancers to manage traffic and keep services available.

1

Create the resource group and virtual machines

Write Azure CLI commands to create a resource group called MyResourceGroup in the eastus region, and create two virtual machines named VM1 and VM2 inside this group.

Azure

# Your Azure CLI commands here to create resource group and VMs

Hint

Use az group create to make the group, then az vm create twice for the two VMs.

2

Create the load balancer and backend pool

Write Azure CLI commands to create a load balancer named MyLoadBalancer in MyResourceGroup and create a backend address pool named MyBackendPool inside the load balancer.

Azure

az group create --name MyResourceGroup --location eastus
az vm create --resource-group MyResourceGroup --name VM1 --image UbuntuLTS --admin-username azureuser --generate-ssh-keys
az vm create --resource-group MyResourceGroup --name VM2 --image UbuntuLTS --admin-username azureuser --generate-ssh-keys
# Your Azure CLI commands here to create load balancer and backend pool

Hint

Use az network lb create with --frontend-ip-name and --backend-pool-name options.

3

Add virtual machines to the backend pool

Write Azure CLI commands to add VM1 and VM2 network interfaces to the backend address pool named MyBackendPool of MyLoadBalancer.

Azure

az group create --name MyResourceGroup --location eastus
az vm create --resource-group MyResourceGroup --name VM1 --image UbuntuLTS --admin-username azureuser --generate-ssh-keys
az vm create --resource-group MyResourceGroup --name VM2 --image UbuntuLTS --admin-username azureuser --generate-ssh-keys
az network lb create --resource-group MyResourceGroup --name MyLoadBalancer --sku Basic --frontend-ip-name MyFrontEnd --backend-pool-name MyBackendPool
# Your Azure CLI commands here to add VM1 and VM2 NICs to backend pool

Hint

Use az network nic ip-config address-pool add to add NICs to the backend pool. The NIC names are usually VM1VMNic and VM2VMNic.

4

Create a load balancing rule for HTTP traffic

Write an Azure CLI command to create a load balancing rule named HTTPRule on MyLoadBalancer that listens on port 80 and forwards traffic to the backend pool MyBackendPool.

Azure

az group create --name MyResourceGroup --location eastus
az vm create --resource-group MyResourceGroup --name VM1 --image UbuntuLTS --admin-username azureuser --generate-ssh-keys
az vm create --resource-group MyResourceGroup --name VM2 --image UbuntuLTS --admin-username azureuser --generate-ssh-keys
az network lb create --resource-group MyResourceGroup --name MyLoadBalancer --sku Basic --frontend-ip-name MyFrontEnd --backend-pool-name MyBackendPool
az network nic ip-config address-pool add --address-pool MyBackendPool --ip-config-name ipconfig1 --nic-name VM1VMNic --resource-group MyResourceGroup --lb-name MyLoadBalancer
az network nic ip-config address-pool add --address-pool MyBackendPool --ip-config-name ipconfig1 --nic-name VM2VMNic --resource-group MyResourceGroup --lb-name MyLoadBalancer
# Your Azure CLI command here to create HTTP load balancing rule

Hint

Use az network lb rule create with the correct ports and names to set up HTTP load balancing.

Practice

1. Why is load balancing important in Azure cloud services?

easy

A. It stores user data securely in the cloud.

B. It automatically updates the operating system on servers.

C. It spreads user traffic across servers to keep apps fast and reliable.

D. It creates backups of all user files daily.

Solution

1. Step 1: Understand load balancing purpose

   Load balancing distributes incoming user requests across multiple servers to avoid overload on any single server.

2. Step 2: Identify benefits in Azure context

   This distribution keeps applications fast and available, even if one server fails.

3. Final Answer:

   It spreads user traffic across servers to keep apps fast and reliable. -> Option C

4. Quick Check:

   Load balancing = traffic spread for speed and reliability [OK]

Hint: Load balancing means sharing traffic to avoid slowdowns [OK]

Common Mistakes:

• Confusing load balancing with data storage
• Thinking it updates software automatically
• Assuming it handles backups

2. Which of the following is required to set up an Azure Load Balancer?

easy

A. A public IP address and a resource group

B. A virtual machine scale set only

C. An Azure SQL database

D. A storage account with blobs

Solution

1. Step 1: Identify Azure Load Balancer requirements

   Azure Load Balancer needs a public IP address to receive traffic and a resource group to organize resources.

2. Step 2: Eliminate unrelated options

   Virtual machine scale sets, SQL databases, and storage accounts are not mandatory for basic load balancer setup.

3. Final Answer:

   A public IP address and a resource group -> Option A

4. Quick Check:

   Load balancer setup = public IP + resource group [OK]

Hint: Load balancer needs public IP and resource group [OK]

Common Mistakes:

• Choosing VM scale set as mandatory
• Confusing with database or storage requirements
• Ignoring the need for a public IP

3. Consider this Azure Load Balancer setup: Two servers receive traffic equally. If one server fails, what happens to incoming requests?

medium

A. Users get an error page immediately.

B. All traffic stops until the failed server is fixed.

C. Traffic is split randomly, including the failed server.

D. Traffic automatically routes only to the healthy server.

Solution

1. Step 1: Understand load balancer health monitoring

   Azure Load Balancer checks server health and stops sending traffic to unhealthy servers.

2. Step 2: Predict traffic routing on failure

   When one server fails, the load balancer routes all traffic to the healthy server automatically.

3. Final Answer:

   Traffic automatically routes only to the healthy server. -> Option D

4. Quick Check:

   Load balancer avoids failed servers for traffic [OK]

Hint: Load balancer sends traffic only to healthy servers [OK]

Common Mistakes:

• Assuming traffic stops completely
• Thinking traffic still goes to failed server
• Believing users see errors immediately

4. You configured an Azure Load Balancer but users report slow app response. What is a likely configuration mistake?

medium

A. Setting the load balancer to distribute traffic evenly

B. Not assigning a public IP to the load balancer

C. Using too many backend servers

D. Enabling health probes for backend servers

Solution

1. Step 1: Check load balancer public IP assignment

   Without a public IP, the load balancer cannot receive external traffic, causing slow or no responses.

2. Step 2: Review other options

   Using many servers or even traffic distribution is normal; health probes improve reliability.

3. Final Answer:

   Not assigning a public IP to the load balancer -> Option B

4. Quick Check:

   Missing public IP causes traffic issues [OK]

Hint: Load balancer needs public IP to receive traffic [OK]

Common Mistakes:

• Blaming too many servers for slowness
• Thinking even traffic distribution causes slow response
• Ignoring the importance of health probes

5. You want to ensure your Azure app stays online even if one server fails. Which load balancing strategy best supports this?

hard

A. Distribute traffic evenly with health probes to detect failures

B. Send all traffic to a single server for simplicity

C. Use a load balancer without health probes

D. Manually switch traffic between servers when one fails

Solution

1. Step 1: Identify strategy for high availability

   Even traffic distribution with health probes ensures traffic only goes to healthy servers, keeping the app online.

2. Step 2: Evaluate other options

   Sending all traffic to one server risks downtime; no health probes means failures go undetected; manual switching is slow and error-prone.

3. Final Answer:

   Distribute traffic evenly with health probes to detect failures -> Option A

4. Quick Check:

   Even distribution + health probes = high availability [OK]

Hint: Use health probes to avoid failed servers automatically [OK]

Common Mistakes:

• Relying on single server for all traffic
• Ignoring health probes in load balancer
• Trying manual traffic switching