Deploy and Configure Azure Load Balancer

Azure Load Balancer is a Layer 4 load balancing service that distributes inbound traffic across a pool of backend compute instances. It operates on the TCP and UDP protocols, using a five-tuple hash of source IP, source port, destination IP, destination port, and protocol to decide which backend instance receives each new flow. Because it works at the transport layer rather than inspecting HTTP payloads, it delivers very low latency and very high throughput, which makes it the default choice for spreading traffic across identical application servers.

The service is built from four pieces that must be wired together before any traffic flows: a frontend IP configuration that clients connect to, a backend address pool holding the instances that serve requests, a health probe that continuously tests each instance, and a load balancing rule that binds the three together and maps a frontend port to a backend port. The health probe is what makes the arrangement highly available: when an instance stops responding, the probe marks it down and the load balancer stops sending it new flows, redirecting them to the remaining healthy instances instead. The Standard SKU adds zone redundancy, larger backend pools, and a secure-by-default posture where traffic must be explicitly allowed by a network security group.

Objectives

By completing this Intermediate challenge, you will be able to:

• Create a Standard SKU public Load Balancer and attach a public IP to its frontend configuration
• Populate a backend address pool with existing virtual machines
• Configure an HTTP health probe to monitor backend instance health
• Define a load balancing rule that binds a frontend port, backend pool, and health probe together
• Access the load balancer public IP and confirm live HTTP traffic from a backend instance

Prerequisites

• Familiarity with the Azure Portal and basic Azure networking concepts (virtual networks, subnets, network security groups)
• An understanding of how virtual machines serve web content over HTTP