Client-side application initiating requests
Cloud / Knowledge library
Elastic Load Balancing
Distributes application and network traffic across AWS targets
Why learn Elastic Load Balancing?
Teams use Elastic Load Balancing to adopt managed load balancing without building the complete underlying platform themselves.
The problem it solves
Distributes traffic across healthy application endpoints
Where it came from
Elastic Load Balancing is Amazon Web Services's offering for managed load balancing. Its closest catalog counterparts are Azure Load Balancer and Google Cloud Load Balancing; they address the same broad need but are not feature-for-feature identical.
Build your understanding
Work through these exercises in order. Try the task before opening a reference.
- Explain the main responsibility of Elastic Load Balancing.
- Choose a workload that fits Elastic Load Balancing.
- Identify one operational tradeoff of Elastic Load Balancing.
- Compare Elastic Load Balancing with Azure Load Balancer.
- Compare Elastic Load Balancing with Google Cloud Load Balancing.
Documentation and sources
- AWS cloud services catalog (aws.amazon.com)
Connect the ideas
Alternatives
Real World Example
Regional Logistics Hub Traffic Management
A regional logistics company managing a fleet of delivery vehicles requires a centralized portal for drivers to upload manifests and receive route updates.
The business problem
The existing monolithic application server frequently crashes during morning shift start times when thousands of drivers simultaneously attempt to authenticate and download their daily routes, leading to significant operational delays.
How this topic solves it
Elastic Load Balancing (ELB) acts as the single point of contact for incoming driver traffic, distributing requests across a fleet of backend application servers. By decoupling the entry point from the compute resources, the system ensures that no single server becomes a bottleneck, allowing the infrastructure to handle concurrent connection spikes gracefully.
- Provision a target group containing multiple application server instances across different Availability Zones.
- Configure the Elastic Load Balancer to listen for incoming HTTPS traffic on port 443.
- Define health check parameters to monitor the status of backend instances.
- Register the target group with the load balancer to begin traffic distribution.
- Update DNS records to point to the load balancer's endpoint.
This diagram illustrates how driver traffic is routed through the load balancer to backend compute resources.
Entry point for traffic distribution
Collection of backend application servers
Individual server processing requests
- Driver Mobile App → HTTPS Request → Elastic Load Balancer
- Elastic Load Balancer → Distributes Traffic → Target Group
- Target Group → Routes to Healthy Target → Compute Instance
Expected business outcome
The logistics portal maintains consistent availability during peak login periods, ensuring drivers receive their manifests without connection timeouts or service interruptions.
Limitations and checks
A primary limitation is the potential for cross-zone data transfer costs if the load balancer is configured to distribute traffic across multiple Availability Zones. Administrators should monitor the 'CrossZoneLoadBalancing' metric in CloudWatch to evaluate if the traffic distribution pattern justifies the associated data transfer expenses.