What is Listeners?
For every load balancer, you must configure at least one listener. The listener defines how your inbound connections are routed to your target groups based on ports and protocols set as conditions.
What is Target groups?
Target groups is a group for your resources that you want your ELB to route requests to. You can configure your ELB with a number of different target groups, each associated with different listener configuration and associated rules.
What is Rules?
Rules are associated to each listener that you have configured within your ELB. They help to define how an incoming request gets routed to which target groups.
Your ELB can contain 1 or more listeners, each listener can contain 1 or more rules and each rule can contain more than 1 condition, and all conditions in the rule equal a single action.
The IF statement resembles the conditions
The THEN statement acts as the action if all the conditions are met
What is health checks?
A health check is the performed against the resources defined within the target group.
These health check allow the ELB to contact each target using a specific protocol to receive a response. If no response is received within a set of thresholds, then the ELB will mark the target as unhealthy and stop sending traffic to that target.
What is internet-facing ELB?
The nodes of the ELB are accessible via the internet and so have a public DNS name that can be resolved to its public IP address, in addition to an internal IP address.
This will allow the ELB to serve incoming requests from the internet before distributing and routing the traffic to your target groups.
Example of this would be a fleet of web servers receiving HTTP or HTTPS requests. When your internet facing ELB communicates with target group, it will only use the internal IP address, meaning that your target group doesn’t need public IP addresses.
What is internal ELB?
An internal ELB only has an internal IP address, this means that it can only serve requests that originate from within your VPC itself.
What is ELB nodes?
For each AZ selected an ELB node will be placed within that AZ
You need to ensure that you have an ELB node associated to any AZs for which you want to route traffic to. Without AZ associated, the ELB will not be able to route traffic to any targets within that AZ even if they are defined within the target group. This is because the nodes are used by the ELB to distribute traffic to your target groups.
What is Cross-zone Load Balancing?
Depending on which ELB option you select, you may have the option of enabling and implementing Cross-zone load balancing within your environment.
Thank you for reading and leave me a comment if you have any questions.