ACA-Cloud1 Alibaba Cloud ACA Cloud Computing Associate Free Practice Exam Questions (2025 Updated)

ApsaraDB RDS for MySQL is a cloud-based relational database service that provides secure, cost-effective, and scalable database solutions for various applications. RDS for MySQL supports creating read-only instances that are synchronized with the primary instance in real time. Read-only instances can handle read requests from applications and reduce the read pressure on the primary instance. This can improve the performance and availability of the database system. Read-only instances can also be used for scenarios such as report analysis, data backup, and disaster recovery.

References:

Overview of read-only ApsaraDB RDS for MySQL instances

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Alibaba Cloud Computing Exam Question 2022

Alibaba Cloud OSS service provides different methods for file uploading, such as simple upload, multipart upload, append upload, and resumable upload1. However, not all of these methods support resuming from break point, which is a feature that allows you to resume an interrupted upload from where it left off. The only method that supports resuming from break point is resumable upload, which is based on multipart upload and uses a checkpoint file to record the upload progress2. The other methods do not support resuming from break point, and will either overwrite or append to the existing object if the upload is interrupted and retried.

References: 1: Alibaba Cloud Academy, “OSS Upload Methods”, https://edu.alibabacloud.com/elearning/lesson/ACA-Cloud-Computing-Certification/lesson-2-oss-upload-methods  2: Alibaba Cloud, “Resumable upload”, https://www.alibabacloud.com/help/doc-detail/31991.htm

SQL injection is a common application layer attack that targets the database of a web application. SQL injection exploits a security vulnerability in the application’s software, such as incorrect filtering of user input, that allows an attacker to send malicious SQL statements to the database. These statements can then be executed to steal, modify, or delete data, or even execute commands on the server1. SQL injection can also bypass authentication and authorization mechanisms, and sometimes even impersonate or damage the underlying system2. SQL injection is one of the most common and dangerous web attacks, and it can cause serious damage to the confidentiality, integrity, and availability of web applications3. References: 1: SQL Injection - OWASP2: SQL Injection - Web Application Firewall - Alibaba Cloud Documentation Center3: Web Application Firewall:What is WAF? - Alibaba Cloud.

 Prepaid is a charging mode that allows you to pay in advance for a certain amount of resources for a specified period of time. It is also known as subscription or reserved instance. Prepaid is more suitable for scenarios with relatively fixed traffic, such as an online ticket booking service, because it offers lower prices and more stable performance than pay-as-you-go. Pay-as-you-go is a charging mode that allows you to pay only for the resources you actually use on an hourly basis. It is more suitable for scenarios with unpredictable or fluctuating traffic, such as a news website or a social media platform. Paypal-pay and bitcoin-pay are not valid charging modes for Alibaba Cloud Computing products.

References: 1: Alibaba Cloud Academy, “Charging Modes”, https://edu.alibabacloud.com/elearning/lesson/ACA-Cloud-Computing-Certification/lesson-1-charging-modes

 = 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 size12

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 instance3456

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

 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

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

Alibaba Cloud relational database service (RDS) is a stable, reliable and elastic 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 does not support Oracle database, which is a proprietary database system developed by Oracle Corporation2. If you need to use Oracle database on Alibaba Cloud, you can deploy it on an ECS instance or use the Oracle Database Backup Service3.

References: 1: Alibaba Cloud Academy, “RDS Concepts”, https://edu.alibabacloud.com/elearning/lesson/ACA-Cloud-Computing-Certification/lesson-5-rds-concepts  2: Oracle, “Oracle Database”, https://www.oracle.com/database/  3: Alibaba Cloud, “Oracle Database Backup Service”, https://www.alibabacloud.com/product/oracle-database-backup-service

 D is the correct answer because OSS supports 3 internal data copies, no human intervention is required to recover the data when anything goes wrong. OSS provides high data reliability and durability by storing multiple replicas of data on different devices in the same region. OSS automatically detects and repairs data errors or failures, and ensures data consistency across all replicas. OSS also supports cross-region replication (CRR) to back up data to another region for disaster recovery12

A, B, and C are incorrect answers because they do not reflect the actual backup technology and policies of OSS.

A is incorrect because OSS does not require manual recovery of data, as it automatically handles data errors or failures.

B is incorrect because OSS provides data protection and backup for customers, and customers do not need to safeguard their own data or use offsite backups.

C is incorrect because OSS does not use RAID0+1 configuration of its underlying physical hard disks, but rather uses a distributed storage system that stores multiple replicas of data on different devices.

References: 1: OSS Overview 2: OSS Backup

Auto Scaling is a management service that can automatically adjust elastic computing resources based on your business needs and policies. Auto Scaling supports the following features12:

Elastic Scale-Out: Automatically adds ECS instances to handle increased workloads.

Elastic Scale-In: Automatically removes ECS instances to reduce costs when workloads decrease.

Elastic Self-Health: Automatically replaces unhealthy ECS instances to ensure high availability and reliability.

Scheduled Scaling: Automatically adds or removes ECS instances based on predefined schedules.

Predictive Scaling: Automatically predicts future workloads and adjusts ECS instances accordingly.

Elastic Self-Diagnostic is not a feature supported by Alibaba Cloud Auto Scaling. It is a fictitious term that does not exist in the Alibaba Cloud documentation or course materials. References: 1: Auto Scaling: Automatically Adjusts Computing Resources - Alibaba Cloud 2: Auto Scaling:What is Auto Scaling? - Alibaba Cloud

Alibaba Cloud provides security services for the underlying hardware of cloud computing, such as physical security, network security, host security, and storage security. Alibaba Cloud also provides security isolation between cloud computing tenants, such as virtualization isolation, network isolation, and data isolation. These security services are part of Alibaba Cloud’s shared responsibility model, where Alibaba Cloud is responsible for the security of the cloud infrastructure, while customers are responsible for the security of their applications and data on the cloud. References: Alibaba Cloud Security Services, Alibaba Cloud Security & Compliance Center, Shared Responsibility Model

 Alibaba Cloud CDN can directly accelerate the access to the files stored in OSS and reduce OSS traffic costs. Alibaba Cloud CDN is a global network of points of presence (POPs) that are distributed across the globe. Alibaba Cloud CDN serves to reduce back-to-origin traffic. This in turn prevents network congestion and reduces latency. If you use Alibaba Cloud CDN to accelerate access to OSS, you can benefit from the following advantages1:

Improved user experience: Alibaba Cloud CDN caches the files stored in OSS to the POPs that are nearest to the users. This reduces the distance that the files need to travel and improves the access speed and user experience.

Reduced OSS traffic costs: Alibaba Cloud CDN reduces the number of requests that are sent to OSS. This reduces the OSS traffic costs and the load on the OSS servers.

Enhanced security: Alibaba Cloud CDN supports HTTPS secure acceleration and anti-leech protection. This ensures the security and integrity of the files stored in OSS. References: Use Alibaba Cloud CDN to accelerate access to OSS

Object Storage Service (OSS) is a cloud storage service that provides secure, cost-effective, and scalable storage for various data types, such as images, videos, and documents. OSS can store large amounts of data and support concurrent access from multiple users. OSS can also integrate with other Alibaba Cloud services, such as Media Transcoding Service (MTS), Server Load Balancer (SLB), and Elastic Compute Service (ECS). By using OSS, the portal can offload the storage and delivery of the image content from the ECS instance, which can improve the performance and availability of the application.

Content Delivery Network (CDN) is a distributed network that delivers content to users based on their geographic locations, the origin servers, and the content delivery policies. CDN can accelerate the delivery of static and dynamic content, such as images, videos, and web pages, by caching the content at edge nodes that are closer to the users. CDN can also reduce the network latency and bandwidth consumption, as well as enhance the security and reliability of the content delivery. By using CDN, the portal can speed up the loading of images and improve the user experience.

Therefore, the combination of OSS and CDN can help resolve the storage and performance issue of the portal at the same time. The other combinations are not as effective or suitable for the portal’s scenario. OSS + MTS combination can help with the storage and transcoding of media files, but not with the delivery of images. OSS + RDS combination can help with the storage and management of relational databases, but not with the loading of images. OSS + ECS combination can help with the storage and computing of data, but not with the acceleration of content delivery.

References:

Alibaba Cloud Object Storage Service

Alibaba Cloud Content Delivery Network

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The main purpose of DDoS attack is to make the target server unable to provide service normally, which is one of the network attacks that are most difficult to defend. Comprehensive and Detailed Explanation: A Distributed Denial-of-Service (DDoS) attack is a malicious attempt to disrupt the normal operation of a target server, service, or network by overwhelming it with a flood of internet traffic from multiple sources1. The main purpose of a DDoS attack is to make the target server unable to provide service normally, which is one of the network attacks that are most difficult to defend. A DDoS attack can cause serious damage to the availability, performance, and reputation of the target server, service, or network, and result in significant financial losses and customer dissatisfaction2.

The other options are not accurate descriptions of a DDoS attack. The main target for a DDoS attack is not the database, but the server, service, or network that hosts the database or other applications. A DDoS attack will not try to crack the password through a large number of attempts, but rather try to exhaust the resources of the target server, service, or network. The purpose of a DDoS attack is not to steal confidential information, but rather to disrupt the normal operation of the target server, service, or network. References: 1: What is a DDoS Attack?1 2: Anti-DDoS: Intelligent DDoS Protection Service - Alibaba Cloud2

 RDS allows users to create multiple databases in one RDS instance, as long as the total storage capacity and performance of the instance are not exceeded. This can help users save costs and simplify management. Users can create, delete, and manage databases in the RDS console or by using SQL commands. However, databases with the same name are not allowed in the same instance, and resources are shared among the databases in the same RDS instance, such as CPU, memory, disk, and network bandwidth. References: Operate and Manage a Relational Database on the Cloud, Alibaba RDS Course | Cloud Academy, ACA Cloud Computing Certification - Alibaba Cloud Academy

Elastic Computing Service (ECS) is a cloud computing service that provides scalable, on-demand computing resources for cloud applications. ECS offers elastic computing, elastic storage, and elastic network features to meet different business needs. However, ECS does not provide elastic administration, which means that the management and configuration of ECS resources are not automatically adjusted according to the workload or demand. Users need to manually create, modify, or delete ECS instances, disks, snapshots, security groups, and other resources. Users can also use other Alibaba Cloud services, such as Auto Scaling, Server Load Balancer, and Cloud Monitor, to enhance the elasticity and availability of ECS.

References:

[Alibaba Cloud Elastic Compute Service]

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Alibaba Cloud ACA-Cloud1 ACA Cloud Computing Certification Exam

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

Server Load Balancer (SLB) is a service that distributes traffic among multiple ECS instances to improve the service capabilities of applications. SLB monitors the health of ECS instances in real time and automatically isolates unhealthy instances from the server pool according to the configured health check policy. This ensures that the traffic is only forwarded to healthy instances, thereby improving the availability and fault tolerance of applications. References: ACA Cloud Computing Certification - Alibaba Cloud Academy, E-Learning Courses - Alibaba Cloud Academy, Server Load Balancer - Alibaba Cloud Documentation Center

 B, C, and E are the correct answers according to the ACA Cloud Computing by Alibaba Cloud Academy Reference Materials and documents. Comprehensive and Detailed Explanation: = B, C, and E are the correct answers because they are suitable services for developing a highly available web application using stateless web servers.

B is correct because Server Load Balancer (SLB) is a service that distributes network traffic across groups of backend servers to improve the service capability and application availability. SLB can handle sudden spikes in traffic, minimize response time, and maintain 99.99% availability of the web application. SLB also supports health checks, session persistence, and cross-zone load balancing1

C is correct because Elastic Compute Service (ECS) is a service that provides scalable and high-performance virtual machines for various computing needs. ECS can run stateless web servers that can be easily scaled up or down based on the demand. ECS can also use Auto Scaling to automate the scaling process and Elastic Self-Health to automatically recover from failures. ECS can also leverage the Alibaba Cloud network infrastructure, such as VPC, Express Connect, and Global Accelerator, to optimize the network connectivity and performance of the web servers2

E is correct because Object Storage Service (OSS) is a service that provides massive, secure, and cost-effective storage for static files, such as images, videos, and documents. OSS can store the static content of the web application and reduce the load and cost of the ECS instances. OSS can also integrate with CDN to accelerate the delivery of the static content and improve the user experience and response time of the web application3

A and D are incorrect answers because they are not suitable services for developing a highly available web application using stateless web servers.

A is incorrect because Relational Database Service (RDS) is a service that provides managed database systems, such as MySQL, SQL Server, PostgreSQL, and PPAS. RDS is not a stateless web server, but a stateful data storage and processing service. RDS can be used to store the dynamic data of the web application, but it is not suitable for hosting the web application itself4

D is incorrect because MaxCompute is a service that provides a fast and fully managed big data platform for large-scale data warehousing. MaxCompute is not a stateless web server, but a data analysis and processing service. MaxCompute can be used to perform complex data analytics and machine learning tasks, but it is not suitable for hosting the web application itself.

References: 1: SLB Overview 2: ECS Overview 3: OSS Overview 4: RDS Overview : [MaxCompute Overview]