ACA-Cloud1 ACA Cloud Computing Associate Questions and Answers

 Cloud disks are reliable because they use a distributed file management system with 3 redundant copies to provide block-level data storage for ECS instances, ensuring 99.9999999% data reliability. This means that the data stored on cloud disks is automatically replicated across three different physical servers in the same zone. If one server fails, the data can still be accessed from the other two servers. Cloud disks also support snapshot backup and recovery, which can help users restore data to a previous point in time in case of accidental deletion or corruption. References: Elastic Compute Service (ECS) - Alibaba Cloud Academy, Cloud Disk - Alibaba Cloud Documentation Center

An ECS disk can be used jointly or separately to meet the requirements of different application scenarios. ECS disks are categorized into ephemeral SSD disks and cloud disks. Compared with ephemeral SSD disks, cloud disks are more reliable as they use a triplicate distributed system to provide block-level data storage for ECS instances, ensuring 99.9999999% data reliability.

Alibaba Cloud Auto Scaling service allows you to automatically adjust the number of ECS instances in a scaling group based on your business needs and scaling policies. You can set the minimum and maximum number of instances in a scaling group to limit the range of scaling actions1. When you create a scaling rule, you can specify the number of instances to be added or removed, or the expected number of instances after the scaling action2. You can also create a scheduled task to execute a scaling rule at a specified time or periodically3.

In this question, the customer sets the minimum number of instances to 6 and the maximum number of instances to 8 in the scaling group. This means that the scaling group will always have at least 6 instances and at most 8 instances. The customer also adds a scaling rule to remove 5 instances, and creates a scheduled task based on this rule. However, this scaling rule will not be executed if it violates the minimum and maximum limits of the scaling group. Therefore, when the scheduled task is activated once, the scaling group will only remove 2 instances, which is the difference between the current number of instances (8) and the minimum number of instances (6). The remaining number of instances in the scaling group will be 6, which is the correct answer. References: 1: Create a scaling group - Auto Scaling - Alibaba Cloud Documentation Center2: Create a scaling rule - Auto Scaling - Alibaba Cloud Documentation Center3: Create a scheduled task - Auto Scaling - Alibaba Cloud Documentation Center.

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Explanation

Session persistence feature in Server Load Balancer means that it can forward the access requests from a single user to the same ECS instance within a certain period to ensure session continuity. This feature is useful for applications that require users to maintain a stateful connection with the backend servers, such as online shopping or banking. Session persistence can be enabled by configuring a cookie timeout period or a source IP hash method in the Server Load Balancer console. References: ACA Cloud Computing Certification - Alibaba Cloud Academy, Server Load Balancer - Alibaba Cloud Academy, Session Persistence - Alibaba Cloud Documentation Center

 According to the Alibaba Cloud Academy, business record filing is a process of registering your website information with the provincial communication management bureau where your server is located. The approval requirements for business record filing vary depending on provincial communication management bureaus. Some provinces may require additional materials or procedures for business record filing. Therefore, the statement is true. References: ACA Cloud Computing Exam Preparation Course - Alibaba Cloud, Module 2: Cloud Computing Security, Lesson 2: Business Record Filing, Slide 3.

 A is the correct answer because Auto Scaling supports adding existing ECS instances into the scaling group, whose status however must be running. Running means that the ECS instance is in a normal state and can provide services. Auto Scaling does not support adding ECS instances that are in other states, such as created, stopped, or preparing. Created means that the ECS instance has been created but has not been started yet. Stopped means that the ECS instance has been stopped and cannot provide services. Preparing means that the ECS instance is being initialized and cannot provide services12

B, C, and D are incorrect answers because they are not valid states for adding existing ECS instances into the scaling group.

References: 1: Add existing ECS instances to a scaling group 2: ECS instance lifecycle

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

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
• ACA Cloud Computing Certification Exam Preparation Course

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 the following protocols for the listener configuration:

• HTTP: Hypertext Transfer Protocol, a stateless application-layer protocol that is used to transfer web pages and other resources over the internet.
• HTTPS: Hypertext Transfer Protocol Secure, an extension of HTTP that uses SSL/TLS encryption to provide secure communication between the client and the server.
• TCP: Transmission Control Protocol, a reliable, connection-oriented transport-layer protocol that provides reliable data delivery and error recovery.
• UDP: User Datagram Protocol, a connectionless transport-layer protocol that provides fast and efficient data transmission without guaranteeing reliability or order.

SLB does not support the following protocols:

• MPLS: Multiprotocol Label Switching, a data-carrying technique that uses labels to forward packets across a network.
• MQTT: Message Queuing Telemetry Transport, a lightweight publish/subscribe messaging protocol that is designed for constrained devices and low-bandwidth networks.

References:

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

 A and C are the correct answers because they can improve the performance of the platform by reducing the load on the ECS instances and the database server.

• A is correct because using CDN can accelerate the delivery of static content such as CSS and JavaScript files, which can reduce the bandwidth consumption and latency of the ECS instances. CDN can also cache the content in edge nodes closer to the end users, which can improve the user experience and response time of the platform1
• C is correct because using RDS can replace the existing self-built database, which can provide better database performance, reliability, security, and scalability. RDS can also handle the backup, recovery, monitoring, and maintenance of the database, which can reduce the management overhead and cost of the platform. Moreover, creating RDS read-only instances can handle read-only requests, which can reduce the workload on the master RDS instance and improve the database availability and performance23

References: 1: CDN Overview 2: RDS Overview 3: RDS Read-only Instances

Server Load Balancer (SLB) is a service that distributes network traffic across multiple ECS instances to improve the service capabilities of applications. By using SLB, you can increase the availability and fault tolerance of your applications. You can also use SLB with Auto Scaling to dynamically adjust the number of ECS instances based on the traffic load. Multiple lower-configuration I/O-optimized ECS instances can be used with SLB to deliver a high-availability architecture that can handle traffic spikes and reduce costs.

References:

• Alibaba Cloud Server Load Balancer
• Alibaba Cloud Elastic Compute Service
• ACA Cloud Computing Certification Exam Preparation Course

Alibaba Cloud provides anti-DDoS products of different levels to protect your applications and data from DDoS attacks. Among them, Anti-DDoS Service Pro is the most suitable product for ensuring high service availability under DDoS attacks. Anti-DDoS Service Pro is a proxy-based mitigation service that diverts network traffic to the Alibaba Cloud global anti-DDoS network through DNS resolution, mitigates volumetric DDoS attacks and resource exhaustion DDoS attacks, and ensures the stability and availability of your origin servers1. Anti-DDoS Service Pro provides the following features and benefits2:

• Over 10 Tbit/s mitigation capacity: Anti-DDoS Service Pro can defend against large-scale DDoS attacks at the Tbit/s level and ensure high service availability.
• AI-enabled for mitigating sophisticated attacks: Anti-DDoS Service Pro can automatically detect and mitigate sophisticated DDoS attacks, such as HTTP flood, HTTPS flood, and DNS flood, and quickly adjust protection policies based on the attack characteristics.
• Hiding origin server IPs: Anti-DDoS Service Pro can hide the IP addresses of your origin servers and prevent attackers from bypassing the proxy and directly attacking your origin servers.
• Multiple protection modes: Anti-DDoS Service Pro supports normal protection mode, emergency protection mode, and always-on protection mode, which can be switched based on your business needs and risk levels.
• Comprehensive security reports: Anti-DDoS Service Pro provides comprehensive security reports that display the attack details, protection status, and traffic statistics of your protected domains. References: 1: Anti-DDoS: Intelligent DDoS Protection Service - Alibaba Cloud2: Anti-DDoS Pro and Anti-DDoS Premium features - Anti-DDoS Pro and Anti-DDoS Premium - Alibaba Cloud Documentation Center.

Alibaba Cloud China Connect is a service that can help international companies do business in China by providing them with the necessary infrastructure, compliance, and ecosystem support1. China Connect includes the following services1:

• ICP Support: Alibaba Cloud helps you obtain the Internet Content Provider (ICP) license, which is required for any website hosted in mainland China.
• Office registration support: Alibaba Cloud helps you register a legal entity in mainland China, which is required for some business scenarios such as e-commerce, online payment, and social media.
• Connect your service with Alibaba Group ecosystem: Alibaba Cloud helps you leverage the Alibaba Group ecosystem, which includes platforms such as Taobao, Tmall, Alipay, and DingTalk, to reach millions of potential customers and partners in China.

However, China Connect does not include web hosting, which is a service that allows you to store and deliver your website content on Alibaba Cloud servers. Web hosting is a separate service that you can purchase from Alibaba Cloud, and it is not part of China Connect.

References: 1: Alibaba Cloud, “China Connect”, https://www.alibabacloud.com/chinaconnect

 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]

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

 According to the Alibaba Cloud Academy, Alibaba Cloud’s object storage service (OSS) is a cloud storage service that enables you to store, backup, and archive any amount of data in the cloud. OSS is a cost-effective, highly secure, and highly reliable cloud storage solution. The capacity of each bucket is unlimited, and there is no limit on the number of files in a single bucket. Therefore, the statement is false. References: What is OSS? - Alibaba Object Storage Service Course - Cloud Academy, Object Storage Service(OSS): Store Data Safely In The Cloud - Alibaba Cloud Blog

 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

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

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]
• ACA Cloud Computing Certification Exam Preparation Course
• Alibaba Cloud ACA-Cloud1 ACA Cloud Computing Certification Exam