When using Alibaba Cloud OSS, you can set access control in three different levels, which are bucket level, object level, and RAM account level. Bucket level access control is the highest level of access control, which determines whether a user can access the bucket and its objects. Bucket level access control can be set to public read/write, public read, or private. Object level access control is the second level of access control, which determines whether a user can access a specific object in the bucket. Object level access control can be set to inherit from the bucket, public read/write, public read, or private. RAM account level access control is the lowest level of access control, which determines whether a user can perform certain operations on the bucket or the object. RAM account level access control can be set by using RAM policies, which specify the actions, resources, and conditions for the access.  References :  Object Storage Service (OSS) - Alibaba Cloud Academy ,  Access Control - Alibaba Cloud Documentation Center

 = A is the correct answer because the memory size of an ECS instance is determined by the instance type, and it cannot be changed independently.  If you want to change the memory size of an ECS instance, you must change the instance type to another one that has a different memory size 1 2

B, C, and D are incorrect answers because the system disk size, data disk size, and number of data disks of an ECS instance can be changed without changing the instance type.  You can use the ECS console or API to resize the system disk or data disks of an ECS instance, or add or remove data disks from an ECS instance 3 4 5 6

References :  1 :  Overview of instance families   2 :  Change the instance type   3 :  Resize disks   4 :  Resize a disk   5 :  Attach or detach data disks   6 :  Attach or detach a data disk

Alibaba Cloud does not support intranet communication between products that are not in the same region, which means that ECS instances in different regions cannot communicate with each other on the intranet, and ECS instances and other products in different regions, such as ApsaraDB for RDS and OSS instances, cannot communicate with each other on the intranet. However, this does not mean that Server Load Balancer cannot be deployed for ECS instances in various regions. Server Load Balancer is a service that distributes traffic among multiple ECS instances according to the configured forwarding rules. It can be used to balance the load and improve the service availability and fault tolerance of applications.  Server Load Balancer supports cross-region deployment, which means that it can distribute traffic to ECS instances in different regions 1 2 .  References:   1 : ACA Cloud Computing Exam Preparation Course - Alibaba Cloud 3   2 : Server Load Balancer - Alibaba Cloud Documentation Center 4

Server Load Balancer (SLB) is a ready-to-use service that seamlessly integrates with Elastic Compute Service (ECS) to manage varying traffic levels without manual intervention.  SLB distributes incoming traffic among multiple ECS instances according to the configured forwarding rules, increasing the service capabilities and fault tolerance of your applications 1 .  SLB supports Layer-4 (TCP/UDP) and Layer-7 (HTTP/HTTPS) load balancing, health checks, session persistence, cross-zone disaster recovery, and other advanced features 2 .

References :  1 : Alibaba Cloud Academy, “Server Load Balancer”, https://edu.alibabacloud.com/elearning/lesson/ACA-Cloud-Computing-Certification/lesson-4-server-load-balancer  2 : Alibaba Cloud, “What is Server Load Balancer?”, https://www.alibabacloud.com/help/doc-detail/27539.htm

 RDS for MySQL is a  Platform as a Service (PaaS)  product that provides a complete database solution on Alibaba Cloud. It is fully compatible with MySQL and supports various MySQL features, such as transactions, views, triggers, stored procedures, and functions. RDS for MySQL frees users from the tasks of managing the underlying operating system, runtime environment, and software packages. Users only need to focus on their business logic and data. Alibaba Cloud takes care of the database installation, configuration, backup, recovery, monitoring, scaling, and security.  References :  MySQL Database Concepts and Operations - Alibaba Cloud Academy ,  Alibaba RDS Course | Cloud Academy ,  ACA Cloud Computing Certification - Alibaba Cloud Academy

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, when ECS is used with Auto Scaling, the number of ECS instances is automatically adjusted based on traffic.  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.

 An ECS image is a copy of data from one or more disks that are attached to an ECS instance. You cannot retrieve data directly from an ECS image and use it right away. You need to create an ECS instance from the image first, and then access the data on the disks of the instance.  References:   Elastic Compute Service:Image overview