ACA-Cloud1 Questions and Answers

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

Alibaba Cloud does not support intranet communication between products that are not in the same region, which means that ECS instances in different regions cannot communicate with each other on the intranet, and ECS instances and other products in different regions, such as ApsaraDB for RDS and OSS instances, cannot communicate with each other on the intranet. However, this does not mean that Server Load Balancer cannot be deployed for ECS instances in various regions. Server Load Balancer 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. Server Load Balancer supports cross-region deployment, which means that it can distribute traffic to ECS instances in different regions12. References: 1: ACA Cloud Computing Exam Preparation Course - Alibaba Cloud3 2: Server Load Balancer - Alibaba Cloud Documentation Center4

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,

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

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

 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

 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

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

 The issue that Company B faces is that their music files stored in OSS are being downloaded by unauthorized users who access them through search engines, rather than through their website. This is called leeching, which is a form of bandwidth theft that consumes the OSS traffic and increases the cost for Company B. To address this issue, Company B can limit the access sources by configuring the “Anti-leech settings” of OSS bucket attributes. Anti-leech settings allow the bucket owner to specify a referer whitelist, which is a list of domain names that are allowed to access the OSS resources. The referer is a part of the HTTP header that indicates the source URL of the request. By setting a referer whitelist, Company B can prevent leeches from accessing their music files directly from search engines or other websites, and only allow access from their own website domain name. This way, Company B can protect their OSS resources from unauthorized access and reduce their OSS traffic costs. The other options are not effective or relevant for addressing the issue. Migrating music files from OSS to data disks for ECS instances would increase the storage and computing costs for Company B, and also reduce the scalability and availability of their music files. Changing the website access mode to HTTPS would enhance the security and encryption of the website, but it would not prevent leeches from accessing the OSS resources through search engines. Introducing SLB for extra protection would improve the load balancing and high availability of the ECS instances, but it would not affect the access control of the OSS resources. References: OSS Anti-Leech Referer Configuration and Error Elimination

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.

Load and Performance Testing Service (LPTS) is a service that helps users to test the performance and stability of their websites, applications, or servers under different load conditions. LPTS can simulate a large number of concurrent users and requests, and generate detailed reports on the response time, throughput, error rate, and other metrics of the target system. LPTS can help users to identify and resolve performance bottlenecks, optimize resource utilization, and ensure the reliability and availability of their online services. References: Load and Performance Testing Service - Alibaba Cloud Academy, Load and Performance Testing Service - Alibaba Cloud Documentation Center

You can upgrade or downgrade an ECS instance’s configuration to meet your business needs. Upgrading an instance’s configuration means increasing the vCPUs, memory, bandwidth, or disk capacity of the instance. Downgrading an instance’s configuration means decreasing the vCPUs, memory, bandwidth, or disk capacity of the instance. You can change the configuration of an ECS instance by using one of the following methods1:

• Change the instance type: You can change the instance type of an ECS instance to adjust the vCPUs and memory of the instance. You can change the instance type of an ECS instance in the following scenarios2:
• Change the bandwidth configuration: You can change the bandwidth configuration of an ECS instance to adjust the network performance of the instance. You can change the bandwidth configuration of an ECS instance in the following scenarios3:
• Change the system disk or data disk: You can change the system disk or data disk of an ECS instance to adjust the disk capacity or performance of the instance. You can change the system disk or data disk of an ECS instance in the following scenarios4:

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, using Auto Scaling is the most preferred method from the perspective of cost and implementation simplicity, as it can dynamically adjust the number of ECS instances according to the traffic fluctuations, without requiring manual operations or wasting resources. The other methods are either too complex, inefficient, or costly to implement. 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.

 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

An ICP license is a permit issued by the Chinese Ministry of Industry and Information Technology (MIIT) that allows websites to operate in China. An ICP license is required for any website that is hosted on a mainland China server, or that wants to use a China-based CDN service to accelerate its access in China. Therefore, you would need to apply an ICP license in the following cases:

• Accelerate your Overseas Website in China: If you have a website that is hosted outside of China, but you want to use Alibaba Cloud’s CDN service to improve its performance and user experience in China, you would need to apply an ICP license for your domain name. This is because Alibaba Cloud’s CDN nodes are located in mainland China, and any website that uses them must comply with the Chinese regulations.
• Launch your website in China: If you want to host your website on an Alibaba Cloud ECS instance or OSS bucket that is located in mainland China, you would need to apply an ICP license for your domain name. This is because any website that is hosted on a mainland China server must have an ICP license to be accessible and legal in China.
• Launch your online shop in China: If you want to run an e-commerce website that sells goods or services to customers in China, you would need to apply an ICP license for your domain name. This is because any website that engages in commercial activities in China must have an ICP license to operate legally and securely in China.

References: What is an ICP License? - Alibaba Cloud Academy, ICP License Application - Alibaba Cloud Documentation Center

 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