Lab 15 – Load Balancer & Application Gateway

Objectives

Prerequisites

Estimated time

45 minutes

Part 1 – Setup: VNet and two web VMs

  1. Search for Resource groups > Create. Name: rg-az104-lab15,

region: East US. Create.

  1. Virtual networks > Create. Name: vnet-lab15, Address space:

10.80.0.0/16, Subnets: subnet-backend with 10.80.1.0/24. Create.

  1. Create two VMs:

- vm-web01 and vm-web02: both Ubuntu 22.04 LTS, StandardB1s,

vnet-lab15/subnet-backend with public IPs (so you can manage them

individually). Create.

  1. On each VM, install nginx with distinct content:

- SSH into vm-web01 and run:

``bash

sudo apt-get update && sudo apt-get install -y nginx

echo "Server 1" | sudo tee /var/www/html/index.html

`

- SSH into vm-web02 and repeat (changing "Server 1" to "Server 2").

Part 2 – Standard Load Balancer

  1. Search for Load balancers > Create.
  2. Basics:

- Name: lb-lab15

- Type: Public

- SKU: Standard

- Region: East US

- Public IP: Create new (e.g., pip-lb15)

  1. Frontend IP configuration:

- Frontend IP name: feLB

- (Public IP already selected above)

  1. Backend pools: Create new

- Name: beLB

- Subnet: select vnet-lab15/subnet-backend

  1. Inbound rules (configure after creation).
  2. Review + create > Create.

Add VMs to backend pool

  1. Go to lb-lab15 > Backend pools > select beLB > + Add.
  2. Select vm-web01 and vm-web02 > Add.

Configure health probe & load-balancing rule

ℹ️

tip

Health probes determine if backend instances are healthy. If a probe fails, the load balancer removes that instance from the rotation until it recovers.

  1. lb-lab15 > Health probes > + Add:

- Name: probe-http

- Protocol: TCP

- Port: 80

- Interval: 5

- Add.

  1. lb-lab15 > Load balancing rules > + Add:

- Name: rule-http

- Protocol: TCP

- Frontend port: 80

- Backend port: 80

- Backend pool: beLB

- Health probe: probe-http

- Session persistence: None

- Add.

Test load balancing

  1. Go to lb-lab15 > Overview > copy the Public IP address.
  2. Open http:// in a browser multiple times — should see alternating

"Server 1" / "Server 2" responses.

Part 3 – Application Gateway with path-based routing

  1. Search for Application gateways > Create.
  2. Basics:

- Name: appgw-lab15

- Tier: Standard v2

- Capacity: 1 instance

- Virtual network: vnet-lab15

- Subnet: Create new subnet-appgw with 10.80.2.0/24

- Public IP: Create new (e.g., pip-appgw15)

  1. Backends:

- Backend pools: select Create new

- Name: backendPool1

- Target type: IP addresses or FQDN

- Targets: add vm-web01's private IP (e.g., 10.80.1.4) and

vm-web02's private IP (e.g., 10.80.1.5)

  1. Configuration (after creation): Rules > configure path-based rules

(see Part 4).

  1. Review + create > Create.

Configure path-based routing

  1. Go to appgw-lab15 > Rules (under Settings) > + Add rule.
  2. Rule name: rule-path
  3. Listener tab:

- Listener name: listener-http

- Frontend IP: select public IP

- Port: 80

- Protocol: HTTP

  1. Backend targets tab:

- Path-based routing: Checked

- Path rules:

- Path: /api/ → backend pool backendPool1

- Path: /images/ → backend pool backendPool1 (or create separate pools)

- Default path: / → backend pool backendPool1

  1. Review + create > Create.

Part 4 – Compare LB SKUs

Aspect Basic LB Standard LB
Backend pool Up to 300 instances, single AVS Up to 1000, VMs/VMSS across zones
SLA None 99.99%
NSG required on backend No (open by default) Yes (secure by default)
Availability Zones No Yes (zone-redundant)
Outbound rules No Yes (explicit SNAT config)

Validation

    1. [ ] Load Balancer distributes traffic across both VMs (alternating responses)
    2. [ ] Health probe configured on port 80
    3. [ ] Application Gateway deployed with backend pool pointing at both VM IPs
    4. [ ] Can articulate Basic vs Standard LB differences and L4 vs L7 use cases

Cleanup

  1. Resource groups > select rg-az104-lab15 > Delete resource group.

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