ACA-Cloud1 Dumps with Practice Exam Questions Answers

 According to the Alibaba Cloud Academy, Alibaba Cloud Object Storage Service (OSS) is a massive, highly available, secured and cost effective storage service. OSS is superior than self-built storage in all these aspects. One of the advantages of OSS is its high availability, which means that the data stored in OSS can be accessed anytime and anywhere with minimal downtime or interruption. OSS achieves high availability by ensuring data reliability of not less than 99.99999999%. Data reliability is the probability that the data stored in OSS is not lost or corrupted. OSS ensures data reliability by automatically backing up data with multiple redundant copies across different devices and facilities. Therefore, the option B is the correct answer that relates to the high availability of OSS. References: What is OSS? - Alibaba Object Storage Service Course - Cloud Academy, [Object Storage Service(OSS): Store Data Safely In The Cloud - Alibaba Cloud Blog]

Session state data is the information that is associated with a specific user session, such as user preferences, shopping cart items, authentication tokens, etc. Session state data needs to be stored in a persistent and scalable way, so that it can be accessed by multiple web servers and survive server failures. Therefore, the suitable services for storing session state data are those that provide reliable, distributed, and high-performance data storage, such as RDS and Table Store.

RDS (Relational Database Service) is a fully managed online database service that supports various database engines, such as MySQL, SQL Server, PostgreSQL, MariaDB, and PPAS (PostgreSQL with Oracle compatibility)1. RDS provides high availability, backup and recovery, security, and monitoring features for your databases. RDS can store session state data in relational tables, and you can use SQL queries to access and manipulate the data.

Table Store is a fully managed NoSQL database service that provides consistent, scalable, and high-performance data storage for structured and semi-structured data2. Table Store organizes data in tables, rows, and columns, and supports primary key and attribute columns. Table Store can store session state data in flexible schemas, and you can use primary key queries or secondary index queries to access and manipulate the data.

References: 1: Alibaba Cloud Academy, “RDS Concepts”, https://edu.alibabacloud.com/elearning/lesson/ACA-Cloud-Computing-Certification/lesson-5-rds-concepts  2: Alibaba Cloud Academy, “Table Store”, https://edu.alibabacloud.com/elearning/lesson/ACA-Cloud-Computing-Certification/lesson-7-table-store

SLB and Auto Scaling are two Alibaba Cloud services that can work together to provide high availability, scalability, and performance for your applications. SLB is a load balancing service that distributes incoming traffic across multiple ECS instances. Auto Scaling is a service that automatically adjusts the number of ECS instances based on your business needs. When you use SLB and Auto Scaling together, you need to follow some best practices and precautions to ensure the optimal performance and reliability of your system. One of the precautions is that SLB instances must have Health Check enabled, or they cannot be used together with Auto Scaling1. Health Check is a feature of SLB that monitors the health status of the backend ECS instances. If an ECS instance becomes unhealthy or fails, SLB automatically stops sending traffic to that instance and redirects the traffic to other healthy instances. This ensures that your application can continue to serve user requests without interruption. Health Check is also essential for Auto Scaling, because Auto Scaling relies on the health status reported by SLB to decide whether to add or remove ECS instances. If an ECS instance is unhealthy, Auto Scaling will automatically replace it with a new one. If the traffic increases and the average health status of the ECS instances decreases, Auto Scaling will automatically add more instances. If the traffic decreases and the average health status of the ECS instances increases, Auto Scaling will automatically remove some instances. Therefore, Health Check is a prerequisite for using SLB and Auto Scaling together. If you disable Health Check, SLB and Auto Scaling will not be able to communicate with each other and coordinate their actions. This may result in performance degradation, service interruption, or resource waste. The other options are incorrect, because they are not necessary or relevant for using SLB and Auto Scaling together. The backend ECS instances under the same SLB instance can have different operating systems, configurations, and scaling groups, as long as they can provide the same service and respond to the same requests. SLB and Auto Scaling do not impose any restrictions on these aspects of the ECS instances. References: Associate SLB instances with or disassociate SLB instances from a scaling group

 You can create a custom image for ECS using data disk snapshots or system disk snapshots. A snapshot is a backup of the data on a disk at a specific point in time. You can use snapshots to create custom images, which are copies of the operating system and applications on a disk. You can use custom images to create ECS instances that have the same operating system, applications, and data as the original disk12.

You cannot create a custom image for ECS using CPU snapshots or memory snapshots. These are not valid terms in Alibaba Cloud. CPU and memory are not persistent storage devices, and they do not store the operating system and applications that are required for creating a custom image34. References: 1: Create a custom image from a snapshot - Alibaba Cloud1 2: What is a custom image? - Alibaba Cloud2 3: What is a CPU? - Alibaba Cloud3 4: What is memory? - Alibaba Cloud4

According to the Alibaba Cloud Academy, a cloud disk snapshot is a point-in-time backup of a cloud disk. You can use snapshots to back up data, create images, or restore data. The operations that you can do on a cloud disk snapshot are snapshot creation, snapshot deletion, snapshot rollback, and snapshot sharing. Snapshot duplicate and snapshot download are not the operations that you can do on a cloud disk snapshot. Therefore, the options A and C are the correct answers. References: Snapshot Overview - Alibaba Cloud Documentation Center, ACA Cloud Computing Exam Preparation Course - Alibaba Cloud, Module 3: Cloud Computing Storage, Lesson 2: Snapshot, Slide 2