|Server Load Balancer||Alibaba Cloud Server Load Balancer is a traffic distribution control service. It distributes incoming application traffic among multiple ECS instances according to the configured scheduling algorithm and listening rules.|
|Server Load Balancer Instance||A Server Load Balancer instance is a running instance of the Server Load Balancer service. To use Server Load Balancer, you must first create a Server Load Balancer instance. The instance ID is a unique identifier for the Server Load Balancer instance.|
|Server Load Balancer IP||The IP address allocated to the Server Load Balancer service after a Server Load Balancer instance is created. According to the instance type, the IP address is either a public IP or a private IP. You can resolve a domain name to a public IP address to provide external services.|
|Listener||A listener defines how the incoming requests are distributed. You must add at least one listener to a Server Load Balancer instance.|
|Backend Server||The ECS instances that process the distributed requests.|
|VServer Group||A group of ECS instances that process the distributed requests. Different listeners can use different VServer groups, which allows you to maintain the request distribution in the listener dimension.|
|Multiple Zones|| |
Multiple zones for Server Load Balancer have already been deployed in most regions for better disaster tolerance.
By default, the instance in the primary zone is used to provide load balancing service, when the instance in the primary zone is unavailable, the instance automatically switches to the backup zone to continue providing service and then switches back to the primary zone when it becomes available. This increases local availability.