Elastic Load Balancing (ELB) is a critical AWS service that automatically distributes incoming application traffic across multiple targets, such as EC2 instances, containers, IP addresses, and Lambda functions. For Solutions Architects focusing on continuous improvement, understanding ELB optimizat…Elastic Load Balancing (ELB) is a critical AWS service that automatically distributes incoming application traffic across multiple targets, such as EC2 instances, containers, IP addresses, and Lambda functions. For Solutions Architects focusing on continuous improvement, understanding ELB optimization is essential.
AWS offers three types of load balancers: Application Load Balancer (ALB) operates at Layer 7, ideal for HTTP/HTTPS traffic with advanced routing capabilities including path-based and host-based routing. Network Load Balancer (NLB) functions at Layer 4, handling millions of requests per second with ultra-low latency, perfect for TCP/UDP traffic. Gateway Load Balancer (GWLB) operates at Layer 3, designed for deploying and scaling virtual appliances like firewalls.
For continuous improvement of existing solutions, architects should consider several optimization strategies. First, enable access logs and CloudWatch metrics to analyze traffic patterns and identify performance bottlenecks. Second, implement connection draining to ensure in-flight requests complete before deregistering targets. Third, configure health checks appropriately to maintain high availability by removing unhealthy instances from rotation.
Cross-zone load balancing ensures even distribution of traffic across all registered targets in enabled Availability Zones, improving fault tolerance. SSL/TLS termination at the load balancer reduces computational overhead on backend instances while maintaining security through AWS Certificate Manager integration.
For cost optimization, evaluate whether pre-warming is necessary for anticipated traffic spikes and consider using target groups efficiently. Implementing sticky sessions when required ensures user session consistency, while weighted target groups enable gradual traffic shifting during deployments.
Architects should also leverage AWS Global Accelerator with ELB for improved global application performance and implement Web Application Firewall (WAF) with ALB for enhanced security. Regular review of security policies, cipher suites, and TLS versions ensures compliance with security best practices while maintaining optimal performance for evolving workloads.
Elastic Load Balancing: A Comprehensive Guide for AWS Solutions Architect Professional
Why Elastic Load Balancing is Important
Elastic Load Balancing (ELB) is a critical component for building highly available, fault-tolerant, and scalable applications on AWS. It ensures that incoming traffic is distributed across multiple targets, preventing any single point of failure and optimizing resource utilization. For the Solutions Architect Professional exam, understanding ELB is essential because it appears in scenarios involving high availability, disaster recovery, and performance optimization.
What is Elastic Load Balancing?
Elastic Load Balancing automatically distributes incoming application traffic across multiple targets such as EC2 instances, containers, IP addresses, and Lambda functions. AWS offers four types of load balancers:
1. Application Load Balancer (ALB) - Operates at Layer 7 (HTTP/HTTPS), ideal for advanced routing, microservices, and container-based applications.
2. Network Load Balancer (NLB) - Operates at Layer 4 (TCP/UDP/TLS), designed for ultra-high performance and low latency requirements. Supports static IP addresses and preserves source IP.
3. Gateway Load Balancer (GWLB) - Operates at Layer 3, used for deploying and scaling third-party virtual appliances like firewalls and intrusion detection systems.
4. Classic Load Balancer (CLB) - Legacy option supporting both Layer 4 and Layer 7, but lacks advanced features of newer load balancers.
How Elastic Load Balancing Works
ELB consists of several key components:
Listeners: Check for connection requests from clients using configured protocols and ports.
Target Groups: Route requests to registered targets based on rules and health checks.
Health Checks: Monitor the health of registered targets and route traffic only to healthy instances.
Availability Zones: ELB distributes traffic across multiple AZs for high availability. Cross-zone load balancing ensures even distribution.
Key Features to Remember: - ALB supports path-based and host-based routing, weighted target groups, and sticky sessions - NLB provides static IP per AZ and supports Elastic IP assignment - GWLB uses GENEVE protocol on port 6081 - Connection draining (deregistration delay) allows in-flight requests to complete - SSL/TLS termination can occur at the load balancer level - Integration with AWS WAF (ALB only), AWS Certificate Manager, and CloudWatch
Exam Tips: Answering Questions on Elastic Load Balancing
Tip 1: When a question mentions ultra-low latency, millions of requests per second, or static IP requirements, think Network Load Balancer.
Tip 2: For scenarios involving HTTP header-based routing, microservices, or Lambda as targets, Application Load Balancer is typically the answer.
Tip 3: Questions about deploying third-party security appliances or inline traffic inspection point toward Gateway Load Balancer.
Tip 4: If preserving the client source IP is mentioned with TCP traffic, NLB is preferred since it preserves source IP by default.
Tip 5: For cross-region failover scenarios, consider using Route 53 with health checks pointing to load balancers in different regions, or use Global Accelerator with NLB endpoints.
Tip 6: When questions mention WebSocket or HTTP/2 support, ALB is the appropriate choice.
Tip 7: For cost optimization questions, remember that ALB and NLB charge based on LCU (Load Balancer Capacity Units), while NLB is generally more cost-effective for high-throughput scenarios.
Tip 8: Private applications requiring internal load balancing should use internal load balancers (scheme: internal) rather than internet-facing ones.
Tip 9: When SSL/TLS offloading is mentioned along with advanced routing, ALB with ACM certificates is the solution.
Tip 10: For questions about gradual traffic shifting during deployments, remember ALB weighted target groups enable blue-green and canary deployments.