All 7 Elastic Load Balancing (ALB, NLB & CLB) questions
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What is Elastic Load Balancing and why is it important for building scalable, highly available applications? How do target groups and health checks work together within an Application Load Balancer to route traffic only to healthy instances? How does path based and host based routing on an Application Load Balancer support directing traffic to different backend services within a single load balancer? How does a Network Load Balancer's preservation of the client's source IP address benefit certain applications compared to an Application Load Balancer? How can Application Load Balancer support sticky sessions, and when is this feature actually necessary for an application? How do you design a load balancer architecture that supports zero downtime blue green or canary deployments for a production application?
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AWS › Elastic Load Balancing (ALB, NLB & CLB)

What is the difference between an Application Load Balancer, a Network Load Balancer, and a Classic Load Balancer?

Beginner

Answer

An Application Load Balancer operates at the application layer and supports advanced routing based on URL paths or hostnames, making it ideal for modern web applications and microservices, a Network Load Balancer operates at the transport layer and is designed for extremely high performance and low latency scenarios needing to handle millions of requests per second while preserving the client's original IP address, and a Classic Load Balancer is an older generation load balancer that has largely been replaced by the more feature rich Application and Network Load Balancer options for new deployments.
aws elbv2 create-load-balancer --name my-alb --type application --subnets subnet-12345 subnet-67890
Real-world example A company running a modern microservices architecture chooses an Application Load Balancer to route traffic to different services based on URL path, while a separate team running an extremely high throughput gaming backend chooses a Network Load Balancer for its ultra low latency performance characteristics.

Common follow-ups: When should a new application still consider using a Classic Load Balancer?;What specific features does an Application Load Balancer support that a Network Load Balancer does not?

Amazon ECS (Elastic Container Service);Amazon API Gateway
All 7 Elastic Load Balancing (ALB, NLB & CLB) questions