What is Load Balancer?

• An AWS Load Balancer is a service that automatically distributes incoming application traffic across multiple targets, such as Amazon EC2 instances, containers, and IP addresses, within one or more availability zones.

• The primary purpose of a load balancer is to improve the availability and fault tolerance of your application.

Different types of Load Balancer.

1. Application Load Balancer (ALB):

   • Works at the application layer (Layer 7 of the OSI model).

   • Ideal for routing HTTP/HTTPS traffic.

   • Supports content-based routing, enabling you to route requests based on the content of the request (e.g., host-based routing).

   • Provides support for WebSocket and HTTP/2 protocols.

   • Well-suited for modern web applications.

2. Network Load Balancer (NLB):

   • Operates at the transport layer (Layer 4 of the OSI model).

   • Routes traffic based on IP protocol data.

   • Best suited for TCP and UDP traffic.

   • Offers high-performance, low-latency balancing.

   • Ideal for applications that require static IP addresses.

3. Classic Load Balancer:

   • The oldest type of load balancer in AWS.

   • Supports both Layer 4 and Layer 7 load balancing.

   • Useful for applications that rely on the older EC2-Classic network.

How Load Balancer works?

1. Traffic Distribution:

   • When a client sends a request to your application, it is directed to the load balancer.

   • The load balancer examines the incoming traffic and forwards it to one of the registered targets.

2. Health Checks:

   • Load balancers regularly perform health checks on registered targets to ensure they are responsive and healthy.

   • Unhealthy targets are automatically removed from the load balancer's rotation.

3. Load Balancing Algorithms:

   • Load balancers use various algorithms to distribute traffic among healthy targets, such as Round Robin, Least Outstanding Requests, or IP Hash.

   • These algorithms help optimize the distribution of requests based on different factors.

4. Auto Scaling Integration:

   • Load balancers work seamlessly with AWS Auto Scaling, enabling your application to scale in or out based on demand.

   • New instances can be automatically registered with the load balancer when added, and instances can be deregistered when they are terminated or become unhealthy.