Let us clarify the question first: What is the Azure Load Balancer? The Azure Load Balancer is a load distribution module for incoming traffic at layer 4 (OSI Reference Model's transportation layer). It provides the even distribution of network traffic across all instances of an application running in the same Azure Data Center.

Currently, there are two types of load balancers:

• Internet-facing Load Balancer: This load balancing module performs the mapping of the incoming data traffic to the private IP addresses and port numbers of the virtual machines and, conversely, also maps the response traffic from the virtual machine to the clients.

The load balancing module requires the following additional resources to perform its tasks:

• Public IP address: A public IP address is needed for the load balancer to receive internet traffic
• Frontend configuration: This associates the public IP address with the load balancer
• Backend address pool: Contains a list of the NICs for all resources that will receive the incoming traffic

Using rules, you can distribute certain types of traffic to multiple virtual machines or services. For example, you can distribute web requests to multiple web servers or web roles.

There are currently two types of rules available:

• Load balancer rules: Load balancer rules are used to distribute network traffic among all the resources in the backend address pool
• Network address translation (NAT) rules: NAT rules are used to route traffic to a specific resource:
  • ILB: This load balancing module performs the mapping of incoming traffic between Azure resources (such as between VNets)

Unlike the Azure Load Balancer, the ILB requires a private IP address. To give the ILB a private IP address, create a frontend configuration and assign it to the VNet or subnet that they want to address.

There are currently two types of Stock Keeping Units available:

• Azure Load Balancer Basic
• Azure Load Balancer Standard (Preview)

There are actually no differences between the SKUs (the same functionality, the same APIs, and so on), but the Azure Load Balancer Standard works with backend pools up to 1,000 devices (with basic being only 100 devices), and also supports availability zones (simultaneous working in several Azure Regions).

I still have a little candy: the use of the Azure Load Balancer Basic is free.