AWS Service

Elastic Load Balancing

ELB distributes traffic across targets. ALB handles Layer 7 HTTP features; NLB handles Layer 4 high-performance TCP/UDP/TLS.

What This Service Solves

ELB distributes traffic across targets. ALB handles Layer 7 HTTP features; NLB handles Layer 4 high-performance TCP/UDP/TLS.

Use ALB for HTTP routing, path/host rules, containers, and web apps.
Use NLB for static IP, ultra-low latency, TCP/UDP, or preserving source IP behavior.

When You Should Not Use It

Do not use a load balancer as a substitute for application health, autoscaling, or database failover.

What AWS Manages and What You Manage

AWS manages load balancer infrastructure. You manage listeners, rules, target groups, health checks, TLS, and security controls.

Security Implications

Use HTTPS listeners, ACM certificates, security groups where supported, WAF with ALB, and private/internal load balancers.

Availability and Scaling

Deploy across multiple AZs and ensure targets exist in each AZ.

Load balancers scale, but target health and backend capacity still matter.

Cost Behavior

Hourly load balancer cost and LCU/NLCU usage, cross-zone traffic, and data transfer are relevant.

Common Integrations

EC2
ECS
Auto Scaling
ACM
WAF
CloudWatch

How AWS Might Present It

Certification-Specific Depth

SAA-C03

Solutions Architect Associate

Know configuration choices, integrations, failure modes, security, operations, and cost tradeoffs.

SOA-C03

CloudOps Engineer Associate

Know configuration choices, integrations, failure modes, security, operations, and cost tradeoffs.

Sources and Review Metadata

Elastic Load Balancing official documentation https://docs.aws.amazon.com/elasticloadbalancing/latest/userguide/what-is-load-balancing.html Reviewed 2026-08-07

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