|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 creating a Server Load Balancer instance. According to the instance type, the IP address is either a public IP or a private IP. You can resolve a domain name to the 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|| |
Server Load Balancer has been already deployed multiple zones in most regions for better disaster tolerance.
By default, an instance in a primary zone is used to provide the load balancing service. However, when the primary zone is unavailable, the instance will automatically switch to the backup zone to continue providing service and then switch back to the primary zone when it becomes available. This increases local availability.