ACP-Cloud1 ACP Cloud Computing Certification Questions and Answers

Alibaba Cloud RDS supports several popular database engines, including MySQL, PostgreSQL, and SQL Server. PPAS (PostgreSQL Plus Advanced Server) is also supported but not Sybase, which is not available as an RDS option on Alibaba Cloud.

After stopping an Alibaba Cloud Elastic Compute Service (ECS) instance, you will not be charged for the instance usage fee or the public bandwidth fee (if applicable) until you start the instance again. However, you will still be charged for the disk usage fee and the snapshot usage fee (if applicable) regardless of which region the instance is located in. This is because the disks and snapshots are still occupying the storage space and need to be billed accordingly. Therefore, the statement is false. References: 1 - Billing FAQ - Alibaba Cloud Document Center - What fees do I need to pay after I stop a Pay-As-You-Go instance?

Alibaba Cloud OSS (Object Storage Service) is the ideal solution for storing large volumes of video data generated by a surveillance system. OSS provides scalable, secure, and cost-effective storage that can accommodate growing data needs without the space limitations of local ECS disks. Additionally, OSS enables easy access to historical data when required, making it well-suited for video storage in use cases like surveillance.

When using Alibaba Cloud SLB to forward layer 7 (HTTP) service requests, SLB will replace the IP address in the HTTP header file to forward requests. Therefore, the source IP address that can be seen on the backend ECS instance is the IP address of SLB instead of the client’s real IP address. However, SLB also provides a feature called X-Forwarded-For (XFF) that can help you obtain the real IP address of the client. XFF is a standard HTTP header field that records the original IP address of the client and the proxy servers that the request passes through. You can enable XFF on the SLB console or by using the API, and then configure your backend ECS instance to parse the XFF header field and get the real IP address of the client. References: 1 - SLB overview - Alibaba Cloud Document Center - Layer 7 listeners - X-Forwarded-For

Alibaba Cloud ECS allows users to set an auto-release time for Pay-As-You-Go instances, giving flexibility in handling temporary workloads without manually releasing instances. Notably, the auto-release time can be adjusted multiple times even after the instance has been created, allowing for modifications as business needs change. This feature provides a convenient way to manage costs by automatically releasing instances when they are no longer needed. However, once the auto-release time is set, it must be adjusted or canceled if changes are required.

This statement is not correct because it is not a good practice to store user access information on each ECS instance in the scaling group. This is because the ECS instances are dynamic and can be added or removed by the Auto Scaling service based on the load and demand. Therefore, the data stored on the ECS instances may be lost or inconsistent if the instances are terminated or replaced. Moreover, this approach does not provide a centralized and unified way to access and analyze the data, which may affect the accuracy and efficiency of the analysis. Therefore, it is better to use other services such as ApsaraDB for RDS, ApsaraDB for Memcache, or OSS to store the user access information in a persistent and scalable manner. References: Auto Scaling, ApsaraDB for RDS, ApsaraDB for Memcache, OSS

Alibaba Cloud SLB instances are assigned a public or private IP address when created, and this IP remains unchanged for the life of the SLB instance. The IP address will only be released when the SLB instance itself is deleted.

RDS for MySQL supports both full backups and incremental backups. A full backup is a complete backup of all data in a database. An incremental backup is a backup of only the data that has changed since the last backup. Incremental backups can reduce the backup time and storage space. You can configure the backup cycle and retention period for both types of backups in the RDS console or by using the API.

The difference between public and private Server Load Balancers (SLBs) is that private SLBs connect to their backend ECS instances using the private network (Intranet) while public SLBs connect to their backend ECS instances using the public network (Internet). This is true according to the Alibaba Cloud documentation on SLB1. Public SLBs are used to distribute traffic from the Internet to ECS instances, while private SLBs are used to distribute traffic within a VPC or a classic network2. References: 1: Server Load Balancer - Alibaba Cloud Documentation Center 2: Create a Server Load Balancer instance - Server Load Balancer - Alibaba Cloud Documentation Center

 You can change the private IP address of an ECS instance after it is created, but you need to stop the instance first. The private IP address must be within the CIDR block of the VPC and the VSwitch that the instance belongs to. You can modify the private IP address of an instance by using the console or the API. References: 3, ACP Cloud Computing Certification - Alibaba Cloud Academy

After stopping an Alibaba Cloud Elastic Compute Service (ECS) instance, you will still be charged for some resources related to that ECS instance, such as disks, snapshots, and public IP addresses, until you release them. The charging policy depends on the billing method and network type of the ECS instance. For pay-as-you-go instances, you can choose whether to enable the No fees for stopped instances feature, which allows you to stop paying for vCPUs and memory when the instance is stopped. However, this feature is only available for VPC-connected instances in some regions1. For subscription instances, you will be charged for the entire subscription period regardless of whether the instance is running or stopped2. References:

1: Billing FAQ - Elastic Compute Service - Alibaba Cloud Documentation Center1

2: Billing overview - Elastic Compute Service - Alibaba Cloud Documentation Center2

In Alibaba Cloud, a Virtual Private Cloud (VPC) provides isolated virtual networking environments where users can configure their own IP address ranges, CIDR blocks, routing tables, gateways, and other network elements. This functionality is critical for users who require an isolated, customizable network environment for their virtual machines in the public cloud. SDN (Software-Defined Networking) and NFV (Network Functions Virtualization) are underlying technologies, while VPN offers secure connectivity but not full virtual network management.

 According to the Alibaba Cloud VPC documentation1, a virtual private cloud (VPC) is a virtual network dedicated to your Alibaba Cloud account. You have full control over your VPC, such as specifying the CIDR block, configuring route tables and gateways, and creating subnets. A VPC is an isolated network environment that provides security and flexibility for your cloud computing resources. You can use a VPC to build a secure and isolated network environment on Alibaba Cloud, design your network topology, and specify intranet IP addresses or CIDR blocks in this network environment as needed. Therefore, option B is the correct choice for your scenario. References: What is a VPC? and Alibaba Cloud Virtual Private Cloud.

Alibaba Cloud Object Storage Service (OSS) is ideal for storing unstructured data, including media files such as pictures, videos, and documents. OSS offers scalable storage, high durability, and easy access, making it well-suited for handling large volumes of unstructured data.

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A. Management and maintenance: To prevent emergent service termination, users need to know the underlying detail like how the data is archived in the resource pool. This is incorrect because cloud storage is designed to abstract the underlying details of how the data is stored and managed from the users. Users do not need to worry about the hardware, software, or network issues that may affect the data availability or reliability. The cloud storage provider is responsible for maintaining and managing the storage infrastructure and ensuring the service continuity1.

B. Service on demand Cloud storage has a huge resources pool, users can apply for and use the resources on demand. This is correct because cloud storage is based on the cloud computing model of service on demand, which means that users can request and access the storage resources as needed, without having to purchase or provision them in advance. Cloud storage providers offer flexible pricing models that allow users to pay only for the storage they use2.

C. High reliability and availability: Provides very high reliability and availability through technologies like 3 redundant copies, automatic failure recovery, etc. This is correct because cloud storage uses various technologies and methods to ensure that the data stored in the cloud is always accessible and durable. For example, cloud storage providers typically replicate the data across multiple servers, regions, or zones to prevent data loss due to hardware failure, natural disaster, or human error. Cloud storage providers also use automatic failure recovery mechanisms to detect and repair any issues that may affect the data integrity or availability3.

D. Ultra-large scale: Data storage can reach TB or even PB level. This is correct because cloud storage can handle massive amounts of data, ranging from terabytes (TB) to petabytes (PB) or even exabytes (EB). Cloud storage providers have the infrastructure and expertise to scale up the storage capacity and performance to meet the growing data needs of users. Cloud storage can support various types of data, such as structured, unstructured, or semi-structured data, and various use cases, such as data backup, data archiving, data analytics, or data sharing.

E. Transparent service: Provides the service through a single SDK. This is incorrect because cloud storage is not a transparent service, but a service that requires users to interact with it through a specific interface or protocol. Cloud storage providers usually offer different types of storage services, such as object storage, block storage, or file storage, each with its own characteristics and features. Users need to choose the appropriate storage service for their data and use the corresponding software development kit (SDK), application programming interface (API), or command-line interface (CLI) to access and manipulate the data.

F. High scalability Storage capacity can be dynamically scaled to meet the needs. This is correct because cloud storage is highly scalable, meaning that users can increase or decrease the storage capacity according to their data needs. Cloud storage providers offer elastic storage services that can automatically adjust the storage resources based on the demand, without requiring users to manually provision or deprovision them. Cloud storage also allows users to scale the storage performance, such as throughput, latency, or bandwidth, to optimize the data access and transfer.

References: 1: What is Cloud Storage? - Cloud Storage Explained - AWS 2: What is Cloud Storage & How Does it Work? | Google Cloud 3: Cloud Storage Reliability and Availability | Cloud Storage Documentation : What is Cloud Storage? - Definition from Techopedia : Cloud Storage Types: Object, Block, and File | IBM : Cloud Storage Scalability | Cloud Storage Documentation

 A DDoS attack is a type of cyberattack that aims to exhaust the resources of a target server or network, such as bandwidth, CPU, memory, or disk space, by sending a large amount of malicious traffic or requests. This can cause the server or network to slow down, crash, or become unavailable to legitimate users. A DDoS attack is not intended to steal confidential information, crack passwords, or target databases, although these may be secondary objectives or consequences of some attacks. A DDoS attack is one of the most common and powerful threats to website security, as it can be launched from multiple sources, use various attack methods, and evade traditional defense mechanisms. According to the DDoS Attack Statistics and Trend Report by Alibaba Cloud, the proportion of volumetric attacks at 50Gbps and above has doubled, and the resources exhaustion attack reached a peak value of 3 million QPS in 2020-2021. References: DDoS Attacks: Sources, Strategies and Practices - Alibaba Cloud, DDoS Attack Statistics and Trend Report by Alibaba Cloud, Use Alibaba Cloud Anti-DDoS Service to Defend DoS Attack, Anti-DDoS Basic - Alibaba Cloud

Alibaba Cloud provides basic security services for ECS instances, which include protection against unexpected remote logins, DDoS attacks, brute-force password cracking, and alerts for potential sensitive information leakage. Key management services (KMS) are available but are not part of the free security services for ECS.

Using a single PUT upload through the console, the maximum file size is 5GB. For larger files, multipart uploading should be used, which allows uploads up to 5TB by splitting files into smaller parts.

When creating an ECS instance in your Alibaba Cloud VPC, you must specify a VSwitch for that instance at the same time. Otherwise, you will not be able to create this ECS instance. This is true according to the Alibaba Cloud documentation on ECS1. A VSwitch is a basic network device of a VPC and is used to connect different cloud product instances deployed in a VPC2. A VSwitch defines a network segment within a VPC and allows you to specify the IP address range, network mask, and gateway for the network segment2. When you create an ECS instance, you must select a VSwitch that belongs to the same zone as the ECS instance3. If you do not specify a VSwitch, the ECS instance will not be able to communicate with other cloud product instances in the VPC or access the Internet. References: 1: Create an instance by using the provided wizard - Elastic Compute Service - Alibaba Cloud Documentation Center 2: What is a VSwitch? - Virtual Private Cloud - Alibaba Cloud Documentation Center 3: Create an instance by using the advanced wizard - Elastic Compute Service - Alibaba Cloud Documentation Center : [VPC FAQ - Virtual Private Cloud - Alibaba Cloud Documentation Center]

To use Alibaba Cloud CDN, you must add your domain to the "CDN Domain Name List" and then modify the domain’s DNS settings to point to the CNAME provided by Alibaba Cloud. Manual cache refresh (option A) is optional and not a necessary step for initial setup, and while monitoring is useful, it is not required for CDN operation, so option D is also not essential.

Intelligent DNS resolution is a feature of Alibaba Cloud DNS that allows users to configure different IP addresses for the same domain name based on the geographic locations or ISPs of the visitors. This way, visitors can access the nearest or optimal server for better performance and availability. Intelligent DNS resolution does not support web page content caching, which is a function of Alibaba Cloud CDN. Alibaba Cloud CDN is a distributed network that delivers content from the origin server to the edge nodes closest to the end users, reducing the network latency and bandwidth consumption. Alibaba Cloud CDN caches the static content of the web pages, such as images, CSS, and JavaScript files, on the edge nodes, so that the users can access them faster and reduce the load on the origin server. A user will receive data from the cache in the first-time access, and then will be updated from the origin site in subsequent requests based on the cache expiration time.

References:

1: Intelligent DNS resolution - Alibaba Cloud DNS - Alibaba Cloud Documentation Center

4: Alibaba Cloud Content Delivery Network (CDN) performs content acceleration with the support of intelligent DNS resolution The following function_________is NOT included in intelligent DNS resolution.

5: Alibaba Cloud DNS:Alibaba Cloud line for intelligent DNS resolution (September 16, 2020) - Alibaba Cloud Documentation Center

To handle high download traffic efficiently, Company F can use Object Storage Service (OSS) to store the installation package and Content Delivery Network (CDN) to distribute it. OSS provides scalable, low-cost storage, while CDN caches content at edge nodes, reducing the load on the ECS instance and improving download speeds for users. This combination helps control bandwidth costs on ECS and provides faster download speeds by serving content closer to end-users.

Alibaba Cloud RDS for MySQL supports cross-zone migration within the same region, allowing users to move their RDS instances to different availability zones if needed. This feature helps enhance disaster recovery and flexibility in resource allocation.

In Alibaba Cloud ECS, whenever an API request is made, a unique identifier called the RequestId is generated and returned. This ID is generated regardless of the request’s success or failure. RequestId serves as a unique identifier for tracking and debugging specific requests within the ECS environment, allowing users to trace and troubleshoot individual API calls. This practice ensures that issues can be resolved more efficiently by tracking the specific request, and it is a common practice across many Alibaba Cloud services.

According to the Alibaba Cloud Academy, a VPC is an isolated network environment that is completely isolated from each other. Each VPC has an independent tunnel ID, and a tunnel ID corresponds to a virtualized network. This means that different VPCs cannot communicate with each other through the tunnel ID. Subnets are not divided like the traditional network environment, but rather are logical divisions of the VPC. Different cloud servers within each subnet are connected by the same router, but different subnets are interconnected by route tables, not switches. ECS instances in a VPC use security group firewalls for Layer 4 network access control, not Layer 2. The internal networks of different VPCs are completely isolated and can be interconnected through IP addresses mapped to the outside, such as NAT Gateway or EIP. References: ACP Cloud Computing Certification Preparation Course - Internetworking with VPC, Alibaba Cloud VPC User Guide

SLB (Server Load Balancer) is a service that distributes network traffic across groups of backend servers to improve the service capability and application availability1. SLB supports HTTPS listeners, which allow you to encrypt the data transmission between clients and SLB instances2. HTTPS is a secure version of HTTP that uses SSL/TLS protocols to provide data encryption, integrity, and authentication3.

To use HTTPS listeners, you need to upload SSL certificates to SLB. SSL certificates are digital certificates that use public key cryptography to verify the identity of a website and encrypt the data exchanged between the website and the visitors4. There are two types of SSL certificates: server certificates and client certificates. Server certificates are issued by trusted certificate authorities (CAs) to verify the identity of the website owner and the domain name. Client certificates are issued by the website owner to verify the identity of the visitors5.

SLB supports both one-way and two-way authentication for HTTPS listeners. One-way authentication means that only the server identity is verified by the client. Two-way authentication means that both the server and the client identities are verified by each other. To use one-way authentication, you only need to upload the server SSL certificate to SLB. To use two-way authentication, you need to upload both the server SSL certificate and the client CA certificate to SLB. The client CA certificate is the root certificate or intermediate certificate of the CA that issues the client certificates.

Therefore, if you want to use SLB and ECS instances to deploy two-way authenticated HTTPS websites, you need to host server SSL certificates and client CA certificates on SLB. SLB can host both SSL certificates and CA certificates, and it supports HTTPS two-way authentication. The other statements are incorrect. References: Server Load Balancer(SLB) - Alibaba Cloud, Add an HTTPS listener - Server Load Balancer - Alibaba Cloud Documentation Center, What is HTTPS? - SSL.com, What is an SSL Certificate? - SSL.com, What is a Client Certificate? - SSL.com, [Configure two-way authentication for an HTTPS listener - Server Load Balancer - Alibaba Cloud Documentation Center]

Auto Scaling in Alibaba Cloud supports event-triggered tasks based on CPU workload, memory utilization rate, inbound and outbound traffic, and Disk IOPS as key metrics for scaling decisions. Average system workload (option C) is not a directly supported metric, making options A, B, D, and E correct. These metrics allow Auto Scaling to respond to real-time performance needs.

For optimal use of SLB with Auto Scaling, enabling Health Check is essential to determine which instances are healthy and ready to handle traffic. SLB doesn’t require all backend servers to have the same OS, be in the same scaling group, or have identical configurations, as it can manage heterogeneous server setups within the same load-balancing group.

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 Cloud Firewall is a service that provides centralized protection for your cloud assets and prevents unauthorized access to your servers. Cloud Firewall can monitor and control the inbound and outbound traffic of your servers, and block malicious requests and attacks. Cloud Firewall can also detect and prevent brute force password cracking attempts by using intelligent algorithms and threat intelligence. Therefore, option A is the correct answer. References: What is Cloud Firewall?, Protect servers from brute force attacks

Security Groups in Alibaba Cloud are VPC-specific. They can only include ECS instances within the same VPC, but they are not restricted to a single zone within the region. This means a Security Group can manage access rules across multiple ECS instances in the same VPC, regardless of the specific zone they are in, as long as they are within the same region. This ensures VPC security compliance across zones in the same region.

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To meet the company’s security requirements, the following solutions should be used together:

A. Enable the VPN on the bastion host (or directly use the VPN image on Alibaba Cloud Marketplace). The administrator uses VPN encrypted communication during O&M. This solution can support secure remote O&M, because VPN (Virtual Private Network) is a technology that creates a secure and encrypted connection over the Internet between the bastion host and the administrator’s device. VPN can protect the data transmitted between the bastion host and the administrator from being intercepted or tampered by malicious third parties1. Alibaba Cloud provides VPN Gateway service that allows users to create VPN connections between VPCs and on-premises data centers, or between VPCs in different regions2. Users can also use VPN images from Alibaba Cloud Marketplace, such as OpenVPN, to create VPN servers on ECS instances3.

B. Build an independent ECS instance as the bastion host or remote logon and O&M, and authorize the bastion host to access ECS instances running other subsystems. This solution can also support secure remote O&M, because a bastion host is a special-purpose ECS instance that acts as a proxy or a gateway for accessing other ECS instances in the VPC. A bastion host can enhance the security of the ECS instances by limiting the exposure of the ECS instances to the public network, and by implementing security policies and monitoring tools on the bastion host4. Alibaba Cloud provides Bastionhost service that allows users to centrally manage the access to cloud servers from external networks and provide secure connections to VPC resources5.

C. Use the security group function of the ECS instance, and respectively deploy ECS instances running different subsystems to independent security groups. This solution can isolate the networks between subsystems, because a security group is a virtual firewall that controls the inbound and outbound traffic of the ECS instances in the group. Users can configure security group rules to allow or deny access based on the network protocol, port, and source IP address. By deploying ECS instances running different subsystems to independent security groups, users can prevent unauthorized access or communication between the subsystems6.

The other solution is not suitable for the company’s scenario, for the following reason:

D. Create multiple ECS instances in the VPC to install subsystems of different departments- Allocate only Intranet IP addresses to all ECS instances, and deploy them in the same security groups. This solution cannot isolate the networks between subsystems, because ECS instances in the same security group can communicate with each other by default, regardless of whether they have intranet or internet IP addresses. Moreover, this solution may also prevent the ECS instances from accessing the internet or providing external services, which may affect the business operation of the company6.

References: What is a VPN? - Virtual Private Network - Cisco, VPN Gateway - Alibaba Cloud, OpenVPN - Alibaba Cloud Marketplace, Bastion Host - Alibaba Cloud Document Center, Bastionhost - Alibaba Cloud, Security groups - Elastic Compute Service - Alibaba Cloud

Changing directory permissions of the system root directory in Linux can have a significant impact on system functionality and services. Modifying these permissions can lead to restricted access for essential system services, potentially causing service disruptions. Proper care is necessary when altering permissions on critical directories.

Latency on an RDS read-only instance can be caused by high loads on the instance itself, inadequate instance specifications, or excessive write operations on the master instance, as these factors directly impact replication delay and resource contention. However, a high load on the ECS instance connected to the RDS read-only instance would not inherently cause latency on the RDS instance, as the ECS and RDS operate independently in terms of processing.

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Once a VPC is created in Alibaba Cloud, its CIDR Block cannot be modified. This design ensures stability and network consistency within the VPC. To change the network range, a new VPC would need to be created with the desired CIDR Block.

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A route table is a set of rules that determine how network traffic is routed within a VPC or between different network instances1. A VRouter is a hub that connects all VSwitches in the same VPC and enables communication between them2. When you create a VPC, a VRouter and a default route table are automatically created for the VPC1. The default route table contains system routes that are automatically generated by the system based on the network topology1. The system routes cannot be modified or deleted1.

However, you can also create custom route tables for your VPC and add custom routes to them1. Custom routes are manually configured by users to route traffic to specific destinations, such as other VPCs, VBRs, VPN Gateways, or NAT Gateways1. Custom routes can be modified or deleted as needed1. You can also associate VSwitches with different route tables to implement fine-grained routing control1.

Therefore, the statement that the routing entries of the route table can not be modified manually is not correct, as it only applies to system routes, not custom routes. The other statements are correct, as each VRouter may have multiple route tables, one default and several custom1; when a VPC is deleted, the corresponding route table is also deleted3; and the default route table cannot be deleted1. References: Route table overview - Virtual Private Cloud - Alibaba Cloud Documentation Center, VRouter overview - Virtual Private Cloud - Alibaba Cloud Documentation Center, Delete a VPC - Virtual Private Cloud - Alibaba Cloud Documentation Center

To confirm a previously unhealthy instance is now healthy, Alibaba Cloud SLB requires three consecutive successful health checks. With a health check interval of 2 seconds and a response timeout of 5 seconds, each check cycle takes up to 5 seconds. Therefore, three successive health checks would take a minimum of 5×3=155 \times 3 = 155×3=15 seconds in total. However, because the health checks are conducted at 2-second intervals, there’s overlap, reducing the actual time to at least 11 seconds for the SLB to mark the instance as healthy.

An event-triggered task is necessary when creating scaling rules based on specific metrics such as CPU utilization. This allows Auto Scaling to monitor real-time metrics and trigger scaling actions when thresholds are met. Scheduled tasks, by contrast, are based on specific times rather than performance metrics.

In Alibaba Cloud RDS, both the master and read-only instances must reside within the same region. Cross-region replication for RDS read-only instances is not supported, as RDS read replicas are designed for high availability and load balancing within a single region.

 Alibaba Cloud CDN can record the real IP address of a visitor in the HTTP header field X-Forwarded-For, which can be obtained by the origin server or the user-defined log of Apache and Nginx. Alibaba Cloud CDN also provides a one-click function to enable the recording of the visitor’s real IP address in the console, which can be viewed in the access log. References:

Obtain the real IP address of a client from the origin server - Dynamic Content Delivery Network - Alibaba Cloud Documentation Center1

Welcome to Alibaba Cloud and find out more detail about cdn real ip2

In Alibaba Cloud SLB, Layer-7 (HTTP/HTTPS) services require enabling the "X-Forwarded-For" header to retrieve the real IP address of clients, while Layer-4 (TCP/UDP) services can obtain the real IP address directly without additional settings.

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Modifying the MAC address of an ECS instance’s NIC can cause network disconnection issues because Alibaba Cloud's VPC network infrastructure relies on consistent NIC configuration. Changing the MAC address may prevent the instance from being identified correctly on the network.

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According to the Alibaba Cloud Elastic Compute Service documentation, if the current public bandwidth does not meet your business requirements, you can upgrade or downgrade the public bandwidth configurations without the need to reboot the ECS instance. This can improve the network performance and response speed of the ECS instance. Upgrading the CPU, memory, or disk of the ECS instance may not solve the issue of bandwidth utilization, and may require rebooting the ECS instance. References: Public bandwidth - Elastic Compute Service

Alibaba Cloud OSS (Object Storage Service) provides extremely high data reliability, typically around 99.99999999%, due to its multi-replica and distributed architecture, ensuring data durability and resilience against single points of failure (SPOF). OSS is designed to store massive amounts of data with high redundancy, making it a preferred choice for businesses that require high reliability and fault tolerance in cloud storage.

Alibaba Cloud RDS offers automatic backups (with point-in-time recovery capabilities, usually up to a certain retention period), backup for both primary and secondary databases, and a dedicated team for backend operations and maintenance (O&M). Real-time patching for security vulnerabilities is generally not automatic but is managed as part of periodic updates or urgent patching requirements, making option D incorrect.

Alibaba Cloud provides two main options for securely connecting a VPC with a traditional IDC: VPN (Virtual Private Network) and a dedicated leased line connection. These methods enable stable and secure communication between the VPC and on-premises environments. HTTP agents and stepping stones (options B and C) are not standard or secure methods for IDC-VPC connectivity.

In Alibaba Cloud’s VPC architecture, a VRouter (Virtual Router) is used to connect multiple VSwitches within a VPC. The VRouter routes traffic between VSwitches, and each VSwitch in a VPC is associated with a route table managed by the VRouter. This setup enables efficient communication between subnets and applies to the entire VPC.

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When changing the specifications of an RDS instance, service interruptions can occur during some upgrade and downgrade operations, depending on the RDS instance type and the complexity of the change. While upgrades are generally supported, certain modifications may result in brief downtime as the system reconfigures resources. This is contrary to option B. Additionally, database version downgrades are restricted, and MySQL 5.1 can indeed be upgraded directly to MySQL 5.6 in Alibaba Cloud RDS.

Alibaba Cloud Object Storage Service (OSS) is ideal for storing large amounts of unstructured data, such as images and videos. By migrating static files to OSS, you can free up disk space on your ECS instance, allowing you to efficiently handle storage needs as your business scales. OSS is a highly scalable and cost-effective solution for handling media files and other static assets.

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Alibaba Cloud SLB can distribute user requests to backend ECS instances, but these ECS instances do not have to have the same specification (CPU, Memory). SLB virtualizes the added group of ECS instances in the same region into an application pool, and you can manage backend servers through either the default server group, a primary server group, or VServer groups. You can add ECS instances of different specifications to the same server group or VServer group according to your needs. SLB supports weighted round-robin (WRR) and weighted least connections (WLC) algorithms to balance the load among backend servers with different weights. References:

SLB overview - Alibaba Cloud

Backend server overview - Alibaba Cloud

What is Server Load Balancer and How It Works - Alibaba Cloud

Server Load Balancer - Alibaba Cloud

Alibaba Server Load Balancer (SLB) Course - Cloud Academy

A. Elastic Compute Service (ECS) image achieve efficient and convenient deployment. This is correct because ECS images are pre-configured operating system environments that can be used to create and launch ECS instances quickly and easily. ECS images can reduce the cost and time of deploying applications on Alibaba Cloud1.

B. Utilizing Content Delivery Network (CDN) can meet the demands for redundant backup. This is incorrect because CDN is not a backup service, but a service that accelerates the delivery of content to end users by caching it at edge nodes. CDN can improve the performance and availability of applications, but it does not provide data redundancy or backup2.

C. Utilizing Server Load Balancer (SLB) and ECS instances can improve data reliability. This is correct because SLB is a service that distributes traffic among multiple ECS instances based on predefined rules. SLB can improve the availability and reliability of applications by eliminating single points of failure and ensuring that requests are routed to healthy instances3.

D. Elastic Compute Service (ECS) snapshot satisfies the needs of rapid recovery of applications and data. This is incorrect because ECS snapshot is a feature that allows users to create point-in-time backups of ECS disks. ECS snapshots can be used to restore data or create new disks, but they do not satisfy the needs of rapid recovery of applications and data. Snapshots are stored in Object Storage Service (OSS), which is a low-cost and durable storage service, but it has higher latency and lower performance than disks4.

E. Reasonable selection of Regions/Zones meets the location needs of application deployment as well as the demands for redundantly backup critical business applications and data. This is correct because regions and zones are the physical locations of Alibaba Cloud data centers. Regions are geographically isolated from each other, and zones are physically independent within the same region. Users can choose the regions and zones that best suit their application deployment needs, such as proximity to customers, compliance with local regulations, and availability of services. Users can also use multiple regions and zones to achieve redundancy and backup for their critical business applications and data.

References: 1: ECS Images 2: CDN Overview 3: SLB Overview 4: ECS Snapshots : Regions and Zones