Classic Load Balancers
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1h 7m

This course provides detail on the AWS Networking and Content Delivery services relevant to the Developer - Associate exam.

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Learning Objectives

  • Understand the basics of APIs
  • Learn about HTTP and internet communication
  • Understand the difference between HTTP and REST
  • Understand what types of APIs API gateway can create
  • The general differences between those API types
  • How an API gateway functions at a high level
  • Give you an understanding of Amazon CloudFront and its high-level process of operation
  • Understand what an elastic load balancer is and what is used for
  • Be aware of the different load balancers available to you in AWS
  • Understand how ELBs handle different types of requests, including those that are encrypted
  • Be able to identify the different components of ELBs
  • Know how to configure ELBs 
  • Know when and why you might need to configure an SSL/TLS certificate



Hello and welcome to this lecture covering the last of the load balancers that are available, the classic load balancer. The classic load balancer supports TCP, SSL/TLS, HTTP, and HTTPS protocols. However, it does not offer as wide a range of features as the other load balancers. It is considered best practice to use the ALB over this classic load balancer unless you have an existing application running in the EC2-Classic network. Now, many of you will be unfamiliar with the EC2-Classic platform, and this is because it is no longer supported for newer AWS accounts. In fact, any account created after the 12th of April 2013 will not support EC2-Classic. 

The EC2-Classic platform was originally introduced when the first release of EC2 was made generally available a number of years ago. The EC2-Classic platform enabled you to deploy your EC2 instances in a single flat network shared with other customers instead of inside a VPC. Although the classic load balancer doesn't provide as many features as the application load balancer, it does offer the following which the ALB does not. It supports EC2-Classic, it supports TCP and SSL listeners, and it has support for sticky sessions using application-generated cookies. Again, the classic load balancer works in much the same way as the other load balancers already discussed, and again, cross-zone load balancing can either be enabled or disabled. Let's now take a look at the creation of a classic load balancer. 

So let's now create the last type of load balancer, the classic load balancer. So again, let's go to EC2. Down the left-hand side to load balancers. We have our previous application load balancer and our network load balancer. Let's now create the classic load balancer. So we go across here to create. Give this a name. I'll just call it classic. Select the VPC that I'd like to do. Now here we have our listener configuration, so for ease, let's just have this listed on port 80. And then here, we need to select our availability zones that we'd like. So let's select this one and also this one here. Once we've selected our subnets for our load balancer, we can then assign security groups. I'm going to use an existing security group that I've created previously. Once that's selected, click on Configure Security Settings. Again, it's telling us we're not using a secure listener. Again, for this demonstration, that's more than okay. Now we can configure our health checks. This will probably look familiar to you when we're discussing the application load balancer. So the port and protocol using and the path, as well, the ping path, which is what the load balancer will check to make sure it can reach to determine if the instance is healthy or not. Once you're happy with those details, select Add EC2 Instances. 

Now here we can select the instances that you want to associate to the load balancer, and this is different to the application load balancer and the network load balancer, where we used target groups. With the classic, we simply select the instances that we want included, so we don't use target groups for a classic load balancer. So for this example, we can select those two options, coming down across to add tags. Put in any tags you want associated for the load balancer. Click on Review and Create, confirm that you're happy with your settings, and then click on Create. And there we have it. So if we go back here, you can now see that we have our three different load balancers that we've created. Here we have our application load balancer, this was our network load balancer, and here we have our classic load balancer. And it's as simple as that. 

Before I finish this lecture, it's a good time to take a quick look at the comparison between the three load balancers that we've looked at. To help with this, AWS Provides a great table to show the feature differences between each ELB, which can be found using the link shown on screen. We can clearly see that the ALB is the most feature-rich. However, the NLB supports some significant differences to that of the ALB, such as support for static IPs, EIPs, and preserving source IP addresses. 

That now brings me to the end of this lecture. Coming up next, I shall be looking at auto scaling and the benefits that this feature brings.



About the Author

William Meadows is a passionately curious human currently living in the Bay Area in California. His career has included working with lasers, teaching teenagers how to code, and creating classes about cloud technology that are taught all over the world. His dedication to completing goals and helping others is what brings meaning to his life. In his free time, he enjoys reading Reddit, playing video games, and writing books.