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A system distributing incoming traffic across multiple servers.
DESCRIPTION
A load balancer evenly distributes network or application traffic across multiple servers to improve availability, scalability, and performance. It performs health checks, removes unhealthy targets, and supports algorithms like round robin, least connections, and hashing. Load balancers operate at L4 or L7, providing routing, SSL termination, and sometimes WAF capabilities. They are essential in cloud-native and microservices architectures to prevent single points of failure.
ALTERNATIVE DEFINITIONS
NGINX
Load balancing distributes client requests across a pool of servers to ensure reliability and performance.
Focuses on reliability and performance outcomes.
AWS
A load balancer distributes incoming application traffic across multiple targets, such as Amazon EC2 instances.
Highlights concrete targets and cloud context.
Cloudflare
Load balancing improves application availability and performance by distributing traffic across servers.
Emphasizes availability and performance improvement.
RELATED TERMS
High Availability Failover Health Check Round Robin Consistent Hashing NGINX HAProxy Application Gateway
COMPETING TERMS
KNOWLEDGE AREAS
Infrastructure Software Engineering Cloud
TARGET AUDIENCE
Cloud Architect DevOps Engineer Software Developer Security Architect IT Manager
EXTERNAL SOURCES
- Wikipedia - Load balancing (computing)
- NGINX - Load balancing concepts and algorithms
- HAProxy - HAProxy load balancing documentation
- AWS - Elastic Load Balancing guide
- Microsoft - Azure Load Balancer overview
TOP QUESTIONS
What is a Load Balancer in modern architectures?
It distributes incoming traffic across multiple servers to improve performance and availability, often with health checks and routing policies.
Category: Definition
Why is a Load Balancer needed?
To avoid single points of failure, scale horizontally, and maintain consistent user experience under variable traffic.
Category: Relevancy
What are L4 vs L7 Load Balancers?
L4 operates at transport layer (TCP/UDP) for basic routing; L7 understands application protocols (HTTP) for advanced routing and policies.
Category: Requirements
What are common Load Balancing algorithms?
Round robin, least connections, weighted distribution, and consistent hashing are typical approaches.
Category: Overview
What mistakes occur with Load Balancers?
Ignoring health checks, misconfiguring session persistence, and failing to monitor can degrade performance and reliability.
Category: Mistakes
What are risks if a Load Balancer is misconfigured?
Outages, uneven traffic distribution, security exposure, and increased latency can result.
Category: Risks
What alternatives compete with Load Balancers?
Service meshes and reverse proxies provide alternative or complementary traffic management patterns.
Category: Alternatives
How to learn Load Balancing quickly?
Practice with NGINX or HAProxy locally, read vendor docs, and experiment with algorithms and health checks.
Category: HowTo
What is SSL termination in Load Balancers?
It offloads TLS decryption at the balancer, simplifying certificate management and reducing server CPU usage.
Category: Overview