ACA-Cloud1 ACA Cloud Computing Associate Questions and Answers

 A company wants to use Alibaba Cloud service to replace their self-built database, which of the following services should it choose? The best answer is ApsaraDB for RDS, which is a stable, reliable, cost-effective, and scalable online database service that supports most mainstream database engines, including MySQL, SQL Server, PostgreSQL, PPAS (highly compatible with Oracle), and MariaDB1. ApsaraDB for RDS is based on the Apsara Distributed File System and high-performance SSDs of Alibaba Cloud, and provides various features such as backup and recovery, performance monitoring, security, and disaster recovery2. By using ApsaraDB for RDS, the company can reduce the complexity and cost of database management, and focus on their core business.

The other options are not suitable for replacing a self-built database. Server Load Balancer (SLB) 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 applications3. Alibaba Cloud CDN (Content Delivery Network) is a service that delivers content from origin servers to edge nodes, and accelerates the response to user requests. It can be used to improve the user experience and reduce the bandwidth consumption of origin servers4. Deploying more ECS instances is a way to increase the computing resources and scalability of applications, but it does not provide a database service5. References: 1: What is ApsaraDB RDS? - ApsaraDB RDS - Alibaba Cloud1 2: ApsaraDB RDS:What is ApsaraDB RDS? - Alibaba Cloud2 3: Server Load Balancer - Alibaba Cloud Documentation Center3 4: Alibaba Cloud CDN - Alibaba Cloud4 5: Elastic Compute Service (ECS) - Alibaba Cloud5

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.

Alibaba Cloud Architecture Design Training is a service that provides professional guidance and best practices for designing cloud architectures that meet the business requirements and goals of the company. Alibaba Cloud Architecture Design Training can help the company to understand the cloud migration process, select the appropriate Alibaba Cloud products and services, design a secure, reliable, scalable, and cost-effective cloud architecture, and implement the migration plan with minimal risks and disruptions. Alibaba Cloud Architecture Design Training can also help the company to optimize the performance and efficiency of the cloud system after the migration.

References:

• Alibaba Cloud Architecture Design Training
• Cloud Migration - Alibaba Cloud Solutions
• ACA-Cloud1 Alibaba Exam Questions and Answers - CertLibrary

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

Server Guard is a cloud-based security service that provides real-time protection for servers against intrusion events, such as brute force password cracking. Server Guard consists of a lightweight agent that is installed on the server and a cloud protection center that analyzes and responds to security threats. Server Guard can help the administrator to reduce the possibility of brute force password cracking by providing the following features1:

• Password cracking protection: Server Guard can detect and block password cracking attempts on servers, such as SSH brute force attacks on Linux servers and RDP brute force attacks on Windows servers. Server Guard can also alert the administrator of the attack source, time, and frequency, and provide suggestions for password strengthening.
• Webshell detection and removal: Server Guard can scan and remove webshells that are maliciously implanted on servers by hackers. Webshells are scripts that allow hackers to remotely execute commands on servers, such as stealing data, uploading files, or launching attacks. Server Guard can identify and delete webshells based on signature matching, behavior analysis, and machine learning.
• Anti-virus and anti-ransomware: Server Guard can detect and terminate various types of malware, such as ransomware, mining programs, backdoor programs, worms, and trojans. Server Guard can also prevent the encryption and deletion of files by ransomware, and restore the files to their original state.
• Security baseline check: Server Guard can perform security baseline checks on servers to evaluate their security posture and compliance level. Server Guard can check more than 40 security items, such as system configuration, account management, network security, and log audit. Server Guard can also provide security hardening suggestions and one-click fixes for the detected issues.
• Security situation awareness: Server Guard can provide a comprehensive and visualized view of the security situation of the servers, such as the number of attacks, the attack sources, the attack types, the attack trends, and the security score. Server Guard can also provide security reports and recommendations for improving the security level of the servers. References: Security Center

Your website has oscillating traffic peaks that are difficult to predict in advance. In this scenario, it is recommended to use SLB and Auto Scaling together with ECS. SLB 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. Auto Scaling is a service that automatically adjusts computing resources based on your volume of user requests. When the demand for computing resources increases, Auto Scaling automatically adds ECS instances to serve additional user requests, or alternatively removes instances in the case of decreased user requests. By using SLB and Auto Scaling together with ECS, you can achieve high scalability and elasticity for your website, and cope with the changing traffic patterns12. References: 1: ACA Cloud Computing Exam Preparation Course - Alibaba Cloud3 2: Auto Scaling: Automatically Adjusts Computing Resources - Alibaba Cloud4

ECS instance filesystem directory operation is not a supported method to create a bucket in OSS. A bucket is a container for objects in OSS, and it is not related to the filesystem of an ECS instance. To create a bucket in OSS, you can use one of the following methods1:

• through OSS API/SDK: You can use the OSS API or SDK to call the PutBucket operation to create a bucket. The OSS API and SDK support various programming languages, such as Java, Python, PHP, C#, and Node.js2.
• through oss cmd tool: You can use the oss cmd tool, which is a command-line tool based on the OSS SDK for Python, to create a bucket by using the ossutil mb command3.
• through cloud console: You can use the Alibaba Cloud console to create a bucket by following the steps in the documentation4. References: 1: Create buckets - Object Storage Service - Alibaba Cloud Documentation Center2: PutBucket - API Reference| Alibaba Cloud Documentation Center3: Create a bucket - OSSUTIL User Guide| Alibaba Cloud Documentation Center4: Create a bucket - Object Storage Service - Alibaba Cloud Documentation Center.

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

 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

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

 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 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

Comprehensive protocol support - ICMP, TCP, UDP, HTTP, HTTPS,

 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]

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

 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

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

Auto Scaling is a management service that can automatically adjust elastic computing resources based on your business needs and policies. It can help you cope with traffic spikes, reduce costs, and improve service availability1. Auto Scaling supports adding an existing ECS instance into the scaling group, which is a collection of ECS instances that share the same scaling configuration and scaling rules2. However, the existing ECS instance must meet certain requirements, one of which is that the instance and the scaling group must be in the same region3. A region is a physical location where Alibaba Cloud deploys its data centers. Each region consists of multiple isolated zones that have independent power grids and networks4. Therefore, the instance and the scaling group do not have to be in the same zone, as long as they are in the same region.

References: 1: Alibaba Cloud Academy, “Auto Scaling”, https://edu.alibabacloud.com/elearning/lesson/ACA-Cloud-Computing-Certification/lesson-6-auto-scaling  2: Alibaba Cloud, “Scaling group”, https://www.alibabacloud.com/help/doc-detail/25948.htm  3: Alibaba Cloud, “Add an existing ECS instance to a scaling group”, https://www.alibabacloud.com/help/doc-detail/25949.htm  4: Alibaba Cloud, “Regions and zones”, https://www.alibabacloud.com/help/doc-detail/40654.htm

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. However, 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