A Classic Load Balancer (CLB) is an older load balancing solution from Amazon Web Services (AWS) that operates at the network level (Layer 4). Compared to the newer Application Load Balancers (ALB) and Network Load Balancers (NLB), the Classic Load Balancer provides basic traffic distribution for applications.
Here are some features and functions of a Classic Load Balancer:
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Layer-4 Load Balancing: The Classic Load Balancer distributes network traffic based on IP addresses and port numbers to the underlying EC2 instances.
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TCP and SSL/TLS Protocol Support: CLB supports load balancing traffic for the Transmission Control Protocol (TCP) and also provides SSL/TLS termination, allowing encrypted connections to be decrypted at the load balancer and then forwarded to the backend instances.
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Simple Health Checks: The Classic Load Balancer can perform basic health checks on the underlying EC2 instances to ensure that only healthy instances receive traffic.
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Automatic Scaling: CLBs support automatic scaling by dynamically responding to the number of healthy instances.
It's important to note that compared to the newer ALB and NLB, the Classic Load Balancer offers fewer advanced application-level features. With the introduction of ALB and NLB, AWS has provided more advanced load balancing solutions that can better meet the specific requirements of modern applications and architectures.
If you are implementing load balancing in AWS, it is recommended to consider using Application Load Balancers (ALB) or Network Load Balancers (NLB), unless you have specific reasons to stick with the Classic Load Balancer.
