Cloud Load Balancing – ALB vs NLB vs Global Load Balancer…

Cloud Load Balancing – ALB vs NLB vs Global Load Balancer Explained

Load balancer selection has gotten complicated with all the options, layers, and pricing models flying around. As someone who’s configured load balancers for everything from simple web apps to complex microservices architectures, I learned everything there is to know about which type fits which situation. Today, I will share it all with you.

Understanding Load Balancer Types

Probably should have led with this section, honestly. The fundamental distinction is which network layer the balancer operates at. Layer 4 (transport) balancers route based on IP addresses and ports. Layer 7 (application) balancers understand HTTP and can route based on URLs, headers, and content.

Multi-cloud strategies provide flexibility and resilience for modern businesses, and load balancing is often the first component requests hit. Understanding your options helps make informed decisions about cost, performance, and capabilities.

Application Load Balancers

AWS ALB, Azure Application Gateway, and GCP HTTP(S) Load Balancing operate at Layer 7. They understand HTTP/HTTPS traffic and can make intelligent routing decisions.

Avoiding vendor lock-in with distributed workloads is harder here because ALBs offer vendor-specific features. AWS ALB does path-based routing differently than Azure Application Gateway. That’s what makes these balancers powerful but less portable.

Use ALBs when you need: path-based routing (/api goes to one service, /app to another), host-based routing (multiple domains on one balancer), WebSocket support, or advanced health checks that verify actual application responses.

Network Load Balancers

AWS NLB, Azure Load Balancer, and GCP Network Load Balancing operate at Layer 4. They’re faster because they don’t inspect packet contents—just forward based on IP and port.

Optimizing costs across providers often favors NLBs. They handle more connections per dollar because they do less processing. For TCP traffic that doesn’t need HTTP features, NLBs make more sense.

Use NLBs when you need: extreme performance (millions of requests per second), TCP/UDP protocols other than HTTP, static IP addresses, or when your application handles its own routing.

Global Load Balancers

Improving availability through redundancy across regions requires global load balancing. AWS Global Accelerator, Azure Front Door, and GCP Global Load Balancing route users to the nearest healthy region.

These services use anycast networking—the same IP address announced from multiple locations. Users automatically connect to the closest point of presence.

Implementation Guidance

Start with assessment of current needs—what protocol does your traffic use, how much do you expect, and do you need geographic distribution?

Plan your architecture carefully. Putting an ALB in front of an NLB wastes money. Understand what each layer provides before stacking them.

Monitor and optimize continuously because load balancer costs scale with traffic. Review your architecture as traffic patterns change.