ACA-Cloud1 ACA Cloud Computing Associate Question and Answers

 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

 ApsaraDB RDS is a cloud-based relational database service that provides secure, cost-effective, and scalable database solutions for various applications. RDS has many advantages over self-built databases, such as high availability, automatic backup, and easy O&M. One of the statements that is wrong when comparing RDS with self-built database is that self-built database supports quick deployment and elastic scaling. This is not true, because self-built database requires users to purchase, install, and configure hardware and software by themselves, which can be time-consuming and complex. Moreover, self-built database cannot easily adjust the computing and storage resources according to the business needs, which can lead to over-provisioning or under-provisioning. RDS, on the other hand, supports quick deployment and elastic scaling, because users can create, modify, or delete RDS instances in minutes through the console or API. Users can also scale up or down the RDS instance specifications, storage capacity, or network bandwidth without affecting the business continuity.

References:

• ApsaraDB RDS
• ACA Cloud Computing Certification Exam Preparation Course
• Which of the following statements is NOT correct, when comparing RDS …

 Elastic Compute Service (ECS) is an IaaS offering on Alibaba Cloud that provides high-performance, stable, reliable, and scalable compute capacity in the cloud. ECS eliminates your need to invest in hardware up front. You can create as many or as few instances as you need in response to changes in requirements or popularity of your workloads. With an ever-growing selection of instance types, ECS provides broader and deeper choices to match a wide spectrum of computing needs. References: What is ECS? - Alibaba Cloud

A large shopping mall deploys a new video surveillance system. The five-floor building in which the mall is located installed 35 HD cameras to monitor the major exits. The surveillance system is deployed on an ECS instance, which has four 2 TB data disks to store video data.

However, video data grows rapidly and the engineers find that the ECS will run out of storage space within 2 weeks.

In this case, OSS is thought to be the best solution for addressing the storage challenge while ensuring quick access to historical video data when needed. OSS is a cloud-based object storage service that provides massive, secure, low-cost, and highly reliable storage for unstructured data such as images, videos, and documents. OSS can store any amount of data and scale up or down on demand. OSS also supports direct video stream storage capabilities, removing the need for a video segmentation cluster. OSS can be accessed through RESTful APIs, SDKs, or web consoles, and can be integrated with other Alibaba Cloud services such as CDN, ECS, and SLB. OSS provides various storage classes for different data storage scenarios, from hot data storage to cold data storage. For video surveillance data, the Infrequent Access (IA) or Archive storage classes can be used to reduce the storage cost while maintaining high data durability and availability123. References: 1: Alibaba Cloud Multimedia Solutions | Video Monitoring & Surveillance1 2: Overview - Object Storage Service - Alibaba Cloud2 3: OSS Concepts - Alibaba Object Storage Service Course - Cloud Academy

 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

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

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.

 Web Application Firewall (WAF) is a cloud-based security service that protects web applications from common web attacks, such as SQL injection, cross-site scripting, and HTTP flood. WAF can also filter out malicious requests and bots, and ensure that only legitimate traffic reaches the web servers. WAF can help online shops to avoid HTTP flood attacks and ensure only genuine customers joining the event.

References:

• Alibaba Cloud Web Application Firewall
• ACA Cloud Computing Certification Exam Preparation Course
• Alibaba Cloud Computing Exam Question 2022

After adding your website to the WAF protection list, you can enable HTTP Flood protection and select an appropriate protection mode for the website

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 applications1. SLB supports Layer-4 (TCP/UDP) and Layer-7 (HTTP/HTTPS) load balancing, health checks, session persistence, cross-zone disaster recovery, and other advanced features2.

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

Alibaba Cloud Monitor service is a service that monitors the running status of Alibaba Cloud resources and custom metrics, and provides alert notifications and data visualization features. A user receives an alert saying that the IOPS utilization rate for an ECS instance exceeds 80%, which means that the disk performance of the instance is reaching its limit and may affect the application performance. To handle the situation, the user may obtain help from Alibaba Cloud through the following methods:

• Check ECS or CloudMonitor product documents: The user can check the official documentation of ECS or CloudMonitor to learn more about the concepts, features, operations, and best practices of these services. For example, the user can find the information about how to view the IOPS utilization rate of an ECS instance, how to optimize the disk performance of an ECS instance, and how to configure alert rules for CloudMonitor.
• Open a ticket to Alibaba Cloud help desk: The user can open a ticket to Alibaba Cloud help desk to get technical support from Alibaba Cloud engineers. The user can choose the ticket type, severity, and product, and describe the problem in detail. The user can also attach screenshots or logs to the ticket to help the engineers diagnose the problem. The user can track the status and response of the ticket in the console.
• Look for answers in Alibaba Cloud forum: The user can look for answers in Alibaba Cloud forum, which is a platform where Alibaba Cloud users can share their experiences, ask questions, and discuss topics related to Alibaba Cloud products and services. The user can search for relevant keywords or tags, browse the existing threads, or post a new question in the forum. The user can also interact with other users or Alibaba Cloud experts in the forum.

D. You cannot obtain any help from Alibaba Cloud is not a correct answer, as Alibaba Cloud provides various ways to help its users with their problems and questions. References: : [What is CloudMonitor? - CloudMonitor - Alibaba Cloud Documentation Center]. : [View the IOPS utilization of an ECS instance - CloudMonitor - Alibaba Cloud Documentation Center]. : [Optimize the disk performance of an ECS instance - Elastic Compute Service - Alibaba Cloud Documentation Center]. : [Configure alert rules - CloudMonitor - Alibaba Cloud Documentation Center].

Domain name binding is a feature that allows you to use your own domain name to access your OSS bucket, instead of using the default OSS domain name. Domain name binding has the following requirements and limitations12:

• Your customized domain name will be audited by Alibaba Cloud. You need to submit a domain name binding request and wait for approval before you can use your own domain name to access your OSS bucket.
• Your customized domain name need to be put on record in MIIT (Ministry of Industry and Information Technology). This is a mandatory requirement for all websites that are hosted in mainland China. You need to provide your domain name information and relevant documents to MIIT and obtain an ICP filing number before you can use your own domain name to access your OSS bucket.

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

According to the Alibaba Cloud Academy, Alibaba Cloud OSS is a cloud storage service that features massive capacity, outstanding security, low cost, and high reliability. To control the access to the files stored on OSS, OSS provides multiple access permissions for each bucket. These bucket permissions are:

• Public-read-write: Anyone, including anonymous users, can perform read and write operations on the objects in the bucket. The owner of the bucket is charged for the requests and traffic generated by these operations. This permission poses a high security risk and is not recommended.
• Public-read: Only the owner of the bucket and authorized RAM users can perform write operations on the objects in the bucket. Anyone, including anonymous users, can perform read operations on the objects in the bucket. The owner of the bucket is charged for the requests and traffic generated by these operations.
• Private: Only the owner of the bucket and authorized RAM users can perform read and write operations on the objects in the bucket. Other users, including anonymous users, are denied access to the objects in the bucket unless they have been granted temporary access permissions by the bucket owner or authorized RAM users.

Therefore, the options B, C, and D are the correct answers that describe the bucket permissions in OSS. References: OSS Security - Alibaba Object Storage Service Course - Cloud Academy, OSS Concepts - Alibaba Cloud Documentation Center

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.

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,

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 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

 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.