ACA-Cloud1 Exam Dumps : ACA Cloud Computing Associate

According to the Alibaba Cloud Academy, Auto Scaling is a service that automatically creates and releases ECS instances based on pre-defined rules in order to scale services to match demand. Furthermore, it can configure server load balancer and relational database service white lists, without any manual intervention. Therefore, using Auto Scaling is the most preferred method from the perspective of cost and implementation simplicity, as it can dynamically adjust the number of ECS instances according to the traffic fluctuations, without requiring manual operations or wasting resources. The other methods are either too complex, inefficient, or costly to implement. References: Introduction to Alibaba Auto Scaling - Cloud Academy, ACA Cloud Computing Exam Preparation Course - Alibaba Cloud, Module 4: Cloud Computing Elasticity, Lesson 1: Auto Scaling, Slide 2.

 A is the correct answer because RDS provides whitelist access policies that allow you to set permitted IP addresses and IP network segments to effectively prevent hackers from attacking the server by port scanning. A whitelist is a security feature that specifies the IP addresses or CIDR blocks that are allowed to access your RDS instance. By default, the whitelist is empty, which means that no IP address can access your RDS instance. You can add IP addresses or CIDR blocks to the whitelist according to your business needs. You can also create multiple whitelist groups and assign different IP addresses or CIDR blocks to each group. This can help you manage the access permissions of different users or applications12

References: 1: Configure a whitelist 2: ApsaraDB RDS:Configure an IP address whitelist

Alibaba Cloud Server Load Balancer (SLB) is a service that distributes network traffic across multiple ECS instances to improve the service capabilities of applications. SLB supports different load balancing algorithms, such as round robin, weighted round robin, and least connections. When using the weighted round robin algorithm, SLB assigns different weights to backend ECS instances based on their processing capabilities. The higher the weight of a backend ECS instance, the more requests it will receive from SLB. However, the weight of a backend ECS instance is not the only factor that determines the load distribution. The number and the weight of other backend ECS instances in the same server group also affect the load balancing result. Therefore, without knowing the weight settings of the remaining 4 ECS instances, we cannot tell what would happen to the load distribution among the 5 ECS instances. The other statements are incorrect because they assume a fixed or proportional load distribution based on the weight of ecs_inst1, which is not necessarily true.

References:

• Alibaba Cloud Server Load Balancer
• [ACA Cloud Computing Certification Exam Preparation Course]
• Alibaba Cloud Computing Exam Question 2022