The maximum number of connections to an RDS instance primarily depends on the memory size of the instance. Higher memory capacity allows for more simultaneous connections, as memory is a key resource in managing and maintaining connections. Alibaba Cloud RDS scales the connection limit based on the instance's memory allocation to ensure stable database performance.

In Alibaba Cloud OSS, a bucket cannot be deleted until all contents, including files and incomplete multipart upload segments, are removed. This prevents accidental data loss by ensuring no objects remain in the bucket before deletion.

To enable Internet access for ECS instances in a VPC, Alibaba Cloud users can use a public SLB with an Internet IP address (Option B) or an SLB with an Elastic IP (EIP) attached (Option C). Both methods allow the SLB instance to receive external requests and forward them to ECS instances within the VPC. Option A is incorrect because it would require a more complex setup without direct Internet access. Option D is incorrect as SLB does not support directly mounting servers from an on-premises data center.

RDS provides whitelist access policies. You can set permitted IP addresses and IP network segments to effectively prevent hackers from attacking the server by port scanning1. A whitelist is a list of IP addresses or CIDR blocks that are allowed to access an RDS instance. By default, the whitelist is empty, which means that no IP address can access the RDS instance. You can add IP addresses or CIDR blocks to the whitelist to allow access from specific sources. You can also modify or delete the whitelist as needed2. Whitelist access policies help improve the security of your RDS instance and protect your data from unauthorized access3. 

 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 OSS provides monitoring functions such as storage space monitoring, tracking service requests (like PUT and GET requests), and monitoring UV (Unique Visitors) to help analyze usage and performance. However, OSS does not specifically track the device type (e.g., PC or mobile) accessing files, making option B incorrect.

For Layer-4 SLB using TCP, the health check determines ECS instance availability based on the successful completion of a TCP 3-way handshake. This ensures that the backend server is reachable and can accept connections, which is critical for reliable TCP-based load balancing.

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OSS does not use a hierarchical structure for objects, but instead uses a flat structure. All elements are stored as objects in buckets. To use OSS in the same manner in which local file systems are used, you can configure Cloud Storage Gateway (CSG).

https://www.alibabacloud.c om/help/doc-detail/31817.htm

 The statement C is correct, because in an OSS bucket, all elements are stored as objects. An object is the basic unit of OSS storage. Each object consists of a unique key, data, and metadata. The key is the name of the object, which is used to identify the object in a bucket. The data is the content of the object, which can be any type of file, such as text, image, video, or audio. The metadata is the information about the object, such as its size, type, creation time, and custom attributes. References: = Object Storage Service:Overview - Alibaba Cloud

Auto Scaling in Alibaba Cloud supports both Pay-As-You-Go and monthly subscription ECS instances within a scaling group. Pay-As-You-Go instances provide flexibility during traffic surges, while idle monthly subscription instances can be added manually to optimize costs and resource usage.

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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.

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

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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 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

Alibaba Cloud Elastic Compute Service (ECS) instances in different security groups are isolated from each other by default, but they can communicate with each other if the security group rules allow it. A security group is a virtual firewall that controls the inbound and outbound traffic of ECS instances. You can configure security group rules to specify which IP addresses, protocols, and ports can access the ECS instances in a security group. You can also authorize other security groups to access the ECS instances in a security group, which enables cross-security group communication. References: Manage ECS instances in security groups, Security FAQ, ECS Security Groups - Alibaba Fundamentals

In SLB, a Listener is configured with policies and forwarding rules that define how the load balancer will handle incoming requests, including protocol, port, and health check configurations. It does not represent an SLB instance itself or a collection of ECS instances, but it plays a crucial role in managing traffic routing and session persistence.

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

CloudMonitor allows users to create custom monitoring metrics and report data, which can then be analyzed and used for alerts. Customized monitoring is flexible, with no set limits on the number of metrics, and users can report data from Alibaba Cloud servers or other devices.

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Alibaba Cloud Express Connect is a service that enables high-bandwidth, reliable, secure, and private connections between different networks, such as VPC networks across regions, Alibaba Cloud accounts, and on-premise data centers1. It supports different connection methods, such as physical connections, virtual border routers, and Express Cloud Connect1.

Scenario A: Intranet communication between VPCs and Smart Access Gateway in customers different branch offices. This scenario can be achieved by using Express Cloud Connect, which is based on the hardware capacities of Smart Access Gateway and provides SD-WAN capabilities1. Express Cloud Connect allows you to connect your branch offices to Alibaba Cloud through a dedicated partner backbone network, and access VPC networks in all regions1.

Scenario B: Intranet communication between a VPC and servers in an external IDC. This scenario can be achieved by using physical connections, which are dedicated network connections between on-premise data centers and VPC networks1. You can lease a line from your ISP or work with an Alibaba Cloud partner to establish a physical connection to Alibaba Cloud1. This way, you can access VPC networks in all regions with high bandwidth and low latency1.

Scenario C: Intranet communication between two VPCs in different accounts and different CIDR Blocks. This scenario can be achieved by using peering connections, which are logical connections that enable communication between VPC networks2. Peering connections support cross-region and cross-account scenarios, and allow you to connect VPC networks with different CIDR blocks2. However, peering connections are not part of Alibaba Cloud Express Connect, but a separate service called Cloud Enterprise Network2.

Scenario D: Intranet communication between two VPCs under the same account in the same region. This scenario can also be achieved by using peering connections, which are logical connections that enable communication between VPC networks2. Peering connections support intra-region and same-account scenarios, and allow you to connect VPC networks with different CIDR blocks2. However, peering connections are not part of Alibaba Cloud Express Connect, but a separate service called Cloud Enterprise Network2. References: 1: Express Connect - Alibaba Cloud 2: Introduction to Cloud Enterprise Network - Alibaba Cloud Document Center

There is no limit on the number of objects that can be stored in a single OSS bucket in Alibaba Cloud. OSS is designed to support massive data storage, allowing users to store an unlimited number of files within a bucket. The only limitations are the bucket storage capacity and account-level quotas.

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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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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.

According to the Alibaba Cloud documentation1, Auto Scaling is a service that automatically adjusts the number of elastic computing resources based on your business demands and policies. When the demand for computing resources increases, Auto Scaling automatically adds ECS instances to ensure sufficient computing capabilities. When the demand decreases, Auto Scaling automatically removes ECS instances to reduce costs.

Auto Scaling supports adding an existing ECS instance into the scaling group, but the instance must meet some requirements1. One of the requirements is that the instance and the scaling group must be in the same region. However, they do not have to be in the same zone. A zone is a physical area within a region that has independent power grids and networks. A region is a geographic area where Alibaba Cloud deploys its resources. Therefore, the correct answer is B.

References:

1: Auto Scaling: Automatically Adjusts Computing Resources - Alibaba Cloud

2: Introduction to Auto Scaling - Alibaba Cloud Document Center

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.

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

Alibaba Cloud RDS uses a master-slave or primary-replica architecture to provide high availability. In the event of a master database failure, automatic failover to the standby instance generally occurs within 30 seconds, helping to minimize downtime and maintain service continuity.

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 Auto Scaling is a service that automatically adjusts the number of ECS instances based on your business needs and policies. You can use Auto Scaling to cope with unpredictable or periodic workloads. Auto Scaling supports three scaling modes: scheduled, dynamic, and fixed1. Dynamic scaling mode allows you to automatically add or remove ECS instances based on CloudMonitor metrics, such as CPU utilization, memory utilization, inbound traffic, and outbound traffic2. You can configure scaling rules and scaling policies to define the conditions and actions for dynamic scaling. For example, you can set a scaling rule to add one ECS instance when the average CPU utilization of the scaling group exceeds 80% for five consecutive minutes3. Dynamic scaling mode is suitable for scenarios where you cannot predict service changes or do not have enough historical data to set a schedule4. References:

1: Auto Scaling overview - Auto Scaling - Alibaba Cloud Documentation Center1

2: Scaling modes - Auto Scaling - Alibaba Cloud Documentation Center2

3: Create a scaling rule - Auto Scaling - Alibaba Cloud Documentation Center3

4: Auto Scaling: Automatically Adjusts Computing Resources - Alibaba Cloud5

Alibaba Cloud Server Load Balancer (SLB) is designed to distribute incoming network traffic across multiple ECS instances within Alibaba Cloud, enhancing fault tolerance and application reliability. Backend servers for SLB must be Alibaba Cloud ECS instances, as SLB is specifically optimized to work within the Alibaba Cloud ecosystem. While it does not support instances from other cloud providers, it ensures integration and performance with Alibaba Cloud’s ECS instances.

The transmission acceleration service for OSS is a feature that allows you to access OSS buckets through a global acceleration endpoint, which can improve the upload and download speed of OSS data across regions. The global acceleration endpoint is a domain name that is resolved to the nearest OSS access point based on the network conditions of the client. This way, the data transmission distance is shortened and the network latency is reduced. Therefore, option C is the correct answer. References: Enable transfer acceleration, Map an acceleration endpoint

When using Auto Scaling with Server Load Balancer (SLB), both the scaling group and the SLB instance must reside in the same region. This is because region-specific configurations enable low-latency connections and proper integration between the resources, ensuring the scaling group can register with the SLB instance effectively.

The ossbrowser is a graphical tool provided by Alibaba Cloud for uploading and downloading files in OSS, offering an intuitive interface for managing objects. Other tools like ossutil and osscmd are command-line tools, while ossfs is used to mount OSS as a file system on Linux, not a graphical tool.

In Alibaba Cloud RDS, read-only instances are synchronized from the master instance but do not allow actions such as creating or deleting databases, configuring backup policies, or changing account authorizations. However, you can configure the read-only instance’s whitelist to control access.

RDS for MySQL supports connections through tools that are compatible with MySQL, such as MySQL-Front, Navicat MySQL, and command-line MySQL commands. SQL Server Management Studio (SSMS) is designed for Microsoft SQL Server and is not compatible with MySQL, so option D is incorrect.

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.

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.

To isolate ECS instances within different VSwitches in a VPC while allowing them to access the internet and other intranet resources, each VSwitch's instances should be in separate Security Groups. By configuring each group to allow all VPC CIDR blocks first and then restricting access to other VSwitch CIDR blocks with a higher priority rule, instances in each VSwitch are isolated without affecting the VPC's external connections. This approach follows Alibaba Cloud's Security Group best practices and CIDR-based access control within VPC environments.

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 According to the Alibaba Cloud SLB documentation1, SLB provides a health check feature that monitors the availability and performance of the backend servers. If a backend server fails the health check, SLB stops routing requests to it and redirects the traffic to other healthy servers. This way, SLB can improve the system’s availability by eliminating single points of failure (SPOFs). Therefore, option A is a correct statement about SLB.

According to the same documentation1, SLB instances are assigned with public IP addresses or private IP addresses based on the network type. If you delete an SLB instance and create a new one, a new IP address will be allocated to the new instance. You cannot specify or reserve an IP address for an SLB instance. Therefore, option B is also a correct statement about SLB.

Option C is incorrect, because SLB does not require you to install or configure any SLB agent on the backend servers. You only need to add the backend servers to the SLB instance and configure the listener and the server group. SLB will automatically distribute the traffic to the backend servers based on the load balancing algorithm and the health check status2.

Option D is also incorrect, because SLB does not provide a function to automatically synchronize data among backend servers. SLB only handles the network traffic distribution and does not interfere with the data on the backend servers. You need to use other methods or tools to synchronize data among backend servers, such as rsync, lsyncd, or Alibaba Cloud Data Transmission Service (DTS)3.

References: Server Load Balancer:SLB overview, Add backend servers, and Data Transmission Service.

 When using Alibaba Cloud SLB, users can enable the health check function to monitor the availability of the backend ECS instances. If a backend ECS instance A is running abnormally, SLB will stop forwarding requests to it and distribute them to other healthy ECS instances. This way, SLB can ensure the high availability and reliability of the service. When the backend ECS instance A is back to normal, SLB will resume forwarding requests to it. SLB performs health checks on the backend ECS instances at regular intervals and updates their status accordingly. Users can configure the health check parameters such as the protocol, port, interval, timeout, and threshold on the SLB console or by using the API. References: 1 - Health checks - Server Load Balancer - Alibaba Cloud Document Center - Health check overview

With a measurement cycle of 5 minutes and a requirement for five consecutive cycles where disk usage exceeds 80%, it would take 5×5=255 \times 5 = 255×5=25 minutes for CloudMonitor to confirm the condition. After confirmation, CloudMonitor typically processes and sends the alert, which may take an additional 5 minutes, totaling approximately 30 minutes before you receive the alert.

Different Alibaba Cloud VPCs are completely isolated from each other by default, but they can communicate with each other over the intranet by using different methods, such as Cloud Enterprise Network (CEN), VPN gateways, VPC peering connections, and PrivateLink. These methods allow you to establish secure and reliable connections between VPCs without exposing your network traffic to the internet. References:

Overview of VPC connections - Alibaba Cloud

Cross-VPC peering - Alibaba Cloud

ALIYUN::VPC::VpcPeerConnection - Alibaba Cloud

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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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.

Elastic Computing on Alibaba Cloud ECS includes features that allow users to quickly start or release multiple instances, upgrade bandwidth without downtime, adjust CPU and memory configurations, and perform horizontal scaling in conjunction with Server Load Balancer (SLB). However, option E is incorrect as there is a limit to the number of disks that can be attached to an ECS instance.

For a service focused on storing and providing fast access to a massive amount of images, the team should use:

Object Storage Service (OSS): For scalable and cost-effective storage of large image datasets.

Elastic Compute Service (ECS): For running the application’s backend and API logic.

Content Delivery Network (CDN): To cache and accelerate image delivery globally, improving access speed for users worldwide.While Auto Scaling is useful for applications with highly variable compute demands, it is not essential for this setup based on the described requirements.

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.

Alibaba Cloud RDS automatically deploys instances in master-slave mode (high availability) without additional configuration or charges. This ensures data redundancy and disaster recovery by maintaining synchronous data replication from the master to the slave instance.

Data Transmission Service (DTS) is a real-time data streaming service that supports data transmission between data sources such as relational databases, NoSQL, and Big Data (OLAP). DTS supports data migration, data synchronization, and change data subscription scenarios. DTS can migrate your data to and from most of the widely used commercial and open source databases. It supports homogeneous migrations such as MySQL to MySQL, as well as heterogeneous migrations between different database platforms, such as Oracle to MySQL. Migrations can be from on-premises databases to RDS or ECS, databases running on ECS to RDS, or vice versa, as well as from one RDS database to another RDS database. DTS also supports database schema replication between instances, which means that DTS can automatically create the same schema as the source database in the target database. DTS also supports warning when source and destination has some unresolved conflict found, such as data type mismatch, primary key conflict, or foreign key constraint violation. DTS can help you resolve these conflicts by providing suggestions or allowing you to modify the data mapping rules. Therefore, the correct answer is C. Supports all of the above functions. References:

1: Data Transmission Service - Alibaba Cloud

2: What is Data Transmission Service? - Alibaba Cloud

3: Database Migration - AlibabaCloud

4: Cloud Migration without Stopping Services: Alibaba Cloud DTS

In non-ForceDelete mode, a scaling group can only be deleted if no ECS instances exist within it and no scaling activities are currently in progress. This ensures that resources are properly released and no scaling operations are disrupted during deletion. Scheduled and event-triggered tasks (option C) and SLB/RDS integrations (option D) do not need to be removed to delete the scaling group in non-ForceDelete mode.

Alibaba Cloud RDS allows multiple databases to be created on a single instance. However, each database within the same instance must have a unique name, and resources are shared among instances unless specified otherwise. Additionally, not all RDS editions support High Availability (HA) mode; HA is typically available in certain editions, like RDS for MySQL and RDS for PostgreSQL.

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