Load balancers are critical infrastructure components that prevent server overload, eliminate single points of failure, and enable horizontal scaling.
Why it matters
- Ensures application availability even when individual servers fail.
- Enables horizontal scaling by adding servers behind the load balancer.
- Improves response times by routing requests to the least-busy server.
- Required for high-availability architectures and disaster recovery.
- Essential for meeting SLA commitments for uptime and performance.
Load balancing algorithms
- Round Robin: Distributes requests sequentially across servers.
- Least Connections: Routes to the server with fewest active connections.
- Weighted: Assigns proportional traffic based on server capacity.
- IP Hash: Routes requests from the same client IP to the same server (session persistence).
- Least Response Time: Chooses the server with fastest response and fewest connections.
Types of load balancers
- Layer 4 (Transport): Routes based on IP address and TCP/UDP port; fast but less flexible.
- Layer 7 (Application): Routes based on HTTP content (URL, headers, cookies); more intelligent but higher overhead.
- Global (GSLB): Distributes traffic across geographically distributed data centers.
- Internal: Balances traffic between services within a private network.
Health checks
- Active checks: Load balancer periodically probes servers for availability.
- Passive checks: Monitors actual traffic for errors and response times.
- Graceful degradation: Remove unhealthy servers from rotation without dropping connections.
High availability patterns
- Active-Passive: Standby load balancer takes over if primary fails.
- Active-Active: Multiple load balancers share traffic with automatic failover.
- DNS failover: GSLB redirects traffic to healthy data centers.
Cloud implementations
- AWS: Application Load Balancer (ALB), Network Load Balancer (NLB), Classic Load Balancer.
- Azure: Azure Load Balancer, Application Gateway.
- GCP: Cloud Load Balancing (HTTP(S), TCP/UDP, Internal).
Related Tools
Related Articles
View all articlesFormal Security Models Explained: Bell-LaPadula, Biba, Clark-Wilson, and Beyond
Master the formal security models that underpin all access control systems. This comprehensive guide covers Bell-LaPadula, Biba, Clark-Wilson, Brewer-Nash, lattice-based access control, and how to choose the right model for your organization.
Read article →Biometric Authentication: Understanding FAR, FRR, and CER for Security Professionals
Master the critical metrics behind biometric authentication systems including False Acceptance Rate (FAR), False Rejection Rate (FRR), and Crossover Error Rate (CER). Learn how to evaluate, tune, and deploy biometric systems across enterprise, consumer, and high-security environments.
Read article →Database Inference & Aggregation Attacks: The Complete Defense Guide
Learn how inference and aggregation attacks exploit aggregate queries and combined data to reveal protected information, and discover proven countermeasures including differential privacy, polyinstantiation, and query restriction controls.
Read article →Physical Security & CPTED: The Complete Guide to Protecting Facilities, Data Centers, and Critical Assets
A comprehensive guide to physical security covering CPTED principles, security zones, access control, fire suppression, and environmental controls for protecting facilities and data centers.
Read article →Explore More Cloud Infrastructure
View all termsAPI Gateway
A service that acts as a single entry point for API requests, handling routing, authentication, rate limiting, and other cross-cutting concerns.
Read more →AWS (Amazon Web Services)
Amazon's comprehensive cloud computing platform offering over 200 services for compute, storage, databases, networking, security, and application development.
Read more →Azure (Microsoft Azure)
Microsoft's cloud computing platform providing integrated services for compute, analytics, storage, networking, AI, and enterprise applications.
Read more →CDN (Content Delivery Network)
A geographically distributed network of servers that cache and deliver web content from locations closest to end users, improving performance and reliability.
Read more →Docker
A platform for developing, shipping, and running applications in lightweight, portable containers that package code with all its dependencies.
Read more →Kubernetes
An open-source container orchestration platform that automates deployment, scaling, and management of containerized applications across clusters of hosts.
Read more →