What is Azure load balancer? what is internal load balancer? What is external load balancer?

Azure Load Balancer is a cloud-based load balancing service provided by Microsoft Azure. It helps distribute incoming network traffic across multiple backend resources such as virtual machines (VMs), virtual machine scale sets, and instances of Azure Kubernetes Service (AKS). Load balancing improves the availability and scalability of applications by ensuring that traffic is evenly distributed and that backend resources are efficiently utilized. Azure Load Balancer offers two main types: Internal Load Balancer and External Load Balancer.

1. Internal Load Balancer (ILB):

   • An Internal Load Balancer (ILB) distributes incoming traffic only within an Azure virtual network (VNet) or subnet. It's not accessible from the public internet.
   • Use cases for Internal Load Balancer include:
     • Load balancing traffic between backend services or applications within a private network.
     • Ensuring high availability and fault tolerance for internal-facing services.
     • Routing traffic to backend VMs or services that are not exposed to the public internet.

2. External Load Balancer (ELB):

   • An External Load Balancer (ELB) distributes incoming traffic from the internet to backend resources in Azure.
   • Use cases for External Load Balancer include:
     • Load balancing web traffic to multiple VMs hosting web applications or APIs accessible from the public internet.
     • Scaling out applications by distributing incoming traffic across multiple instances for improved performance and availability.
     • Providing high availability and fault tolerance for publicly accessible services.

Key features and capabilities of Azure Load Balancer include:

• Layer 4 (Transport Layer) load balancing for TCP and UDP traffic.
• Load distribution algorithms such as round-robin and hash-based distribution.
• Health probes to monitor the health and availability of backend resources and automatically route traffic away from unhealthy instances.
• Public IP address assignment for External Load Balancer to serve incoming internet traffic.
• Integration with Azure Virtual Machines, Virtual Machine Scale Sets, and Azure Kubernetes Service (AKS) for load balancing applications and services.

In summary, Azure Load Balancer is a vital component for ensuring high availability, scalability, and efficient traffic distribution for applications and services hosted in Azure. Internal Load Balancer is used for internal-facing services within a VNet, while External Load Balancer handles incoming internet traffic to public-facing resources.