ACP-Cloud1 Exam Dumps : ACP Cloud Computing Certification

According to the Alibaba Cloud documentation1, Auto Scaling is a service that automatically adjusts the number of elastic computing resources based on your business demands and policies. When the demand for computing resources increases, Auto Scaling automatically adds ECS instances to ensure sufficient computing capabilities. When the demand decreases, Auto Scaling automatically removes ECS instances to reduce costs.

Auto Scaling supports adding an existing ECS instance into the scaling group, but the instance must meet some requirements1. One of the requirements is that the instance and the scaling group must be in the same region. However, they do not have to be in the same zone. A zone is a physical area within a region that has independent power grids and networks. A region is a geographic area where Alibaba Cloud deploys its resources. Therefore, the correct answer is B.

References:

1: Auto Scaling: Automatically Adjusts Computing Resources - Alibaba Cloud

2: Introduction to Auto Scaling - Alibaba Cloud Document Center

In Alibaba Cloud SLB, Layer-7 (HTTP/HTTPS) services require enabling the "X-Forwarded-For" header to retrieve the real IP address of clients, while Layer-4 (TCP/UDP) services can obtain the real IP address directly without additional settings.

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Alibaba Cloud SLB can distribute user requests to backend ECS instances, but these ECS instances do not have to have the same specification (CPU, Memory). SLB virtualizes the added group of ECS instances in the same region into an application pool, and you can manage backend servers through either the default server group, a primary server group, or VServer groups. You can add ECS instances of different specifications to the same server group or VServer group according to your needs. SLB supports weighted round-robin (WRR) and weighted least connections (WLC) algorithms to balance the load among backend servers with different weights. References:

SLB overview - Alibaba Cloud

Backend server overview - Alibaba Cloud

What is Server Load Balancer and How It Works - Alibaba Cloud

Server Load Balancer - Alibaba Cloud

Alibaba Server Load Balancer (SLB) Course - Cloud Academy