Elastic Load Balancing (ELB)

Elastic Load Balancing (ELB) in AWS is instrumental in maintaining high availability and resilience by distributing traffic across multiple EC2 instances.

Basics of Load Balancing

Load balancing is crucial for high availability and preventing single points of failure in applications. ELB distributes incoming application traffic, avoiding bottlenecks and ensuring efficient resource utilization. If an instance fails, ELB reroutes traffic to operational instances, enhancing fault tolerance.

Types of Load Balancers

AWS offers three load balancer types:

• Application Load Balancer (ALB) works at the application layer (Layer 7), suitable for routing based on content or URL.
• Network Load Balancer (NLB) handles high throughput with low latency at the transport layer (Layer 4), perfect for real-time applications.
• Classic Load Balancer (CLB) is an older version that can manage both Layers 4 and 7 traffic but is less flexible than its modern counterparts.

Choose ALB for applications needing URL-based routing, NLB for high-performance requirements, and consider migrating from CLB to modern options for new projects.

Health Checks

ELB's health checks monitor EC2 instances to ensure they are operational. If an instance fails a health check, ELB stops sending traffic to it, only resuming once the instance recovers. Configuring these checks involves setting the check's frequency, path, and failure threshold, which is key to maintaining application performance and user satisfaction.

Key Takeaways

Understanding load balancing, selecting the correct type, and implementing effective health checks are essential for optimizing application performance, availability, and user experience on AWS.