AWS Load Balancing: ALB vs. NLB

By Robert Mutua

Load balancers are a crucial component for every application. They help distribute traffic, keep your resources running, and scale automatically when needed. In this article we will look at two AWS load balancers to help you make an informed decision on which one is best suited for your needs.

What are AWS Load Balancers?

AWS Load Balancers are a vital part of any AWS-based infrastructure. They allow you to distribute incoming traffic across multiple Amazon sources, making your applications more fault-tolerant and scalable. There are two types of load balancers: Application Load Balancers (ALBs) and Network Load Balancers (NLBs).

What is an Application Load Balancer?

An Application Load Balancer is a Layer 7 load balancer that routes traffic to your applications based on advanced application-level routing criteria. ALBs provide features like path-based routing and host-based routing, and can also support containerized applications via AWS Lambda.

What is a Network Load Balancer?

A Network Load Balancer is a Layer 4 load balancer that routes traffic to your applications based on network-level routing criteria. NLBs are ideal for handling high levels of traffic, and can scale to millions of requests per second.

What is a target group?

A target group is a collection of targets, which are the resources that you route traffic to. For example, EC2 instances, Lambda functions, and IP addresses. You can even configure a Application Load Balancer-type Target Group for Network Load Balancers.

Which one should I choose?

Application Load Balancers (ALBs) are best suited for load balancing HTTP and HTTPS traffic. They operate at the application layer (Layer 7), which means they can route traffic based on advanced application-level criteria, such as the content of the request. This makes ALBs ideal for applications that require complex routing, such as microservices or container-based applications.

Network Load Balancers (NLBs) are best suited for load balancing TCP traffic. They operate at the network layer (Layer 4), which means they can route traffic based on basic network criteria, such as IP address and port number. This makes NLBs ideal for applications that don't require advanced routing, such as traditional web applications.

Both ALBs and NLBs are highly available and scalable, so you can be confident that your application will


In conclusion, both ALB and NLB are great choices for load balancing on AWS. They each have their own pros and cons, so it really depends on your specific needs as to which one is the best fit. If you need more control over the traffic routing and how the load is distributed, then ALB is probably a better choice. However, if you want a simpler solution that is easier to set up and manage, then NLB might be a better option.