AWS SAA-C03 真题演练卷 · 第 04 份

To meet the requirements of seamless scaling and high availability across multiple Availability Zones, the ECS service must use Service Auto Scaling to dynamically adjust the number of tasks based on CPU utilization. Additionally, an Application Load Balancer should be used to distribute traffic across tasks running in multiple AZs. Using Fargate simplifies the setup and eliminates the need to manage EC2 instances, while task placement constraints or restricting to a single AZ would violate the high availability requirement.

为了满足跨可用区的无缝扩展和高可用性的要求，ECS 服务必须使用服务弹性伸缩来根据 CPU 利用率动态调整任务数量。此外，Application Load Balancer 应用于在多个可用区中运行的任务之间分配流量。使用 Fargate 可以简化设置并消除管理 EC2 实例的需要，而任务放置约束或限制到单个可用区将违反高可用性要求。

Amazon ECS with AWS Fargate is the best choice for this scenario because it provides a fully managed container orchestration service that integrates seamlessly with AWS services. It abstracts infrastructure management, supports auto-scaling, and ensures high availability, making it an ideal choice for a team with limited Kubernetes expertise.

Amazon ECS 和 AWS Fargate 是此场景的最佳选择，因为它提供了与 AWS 服务无缝集成的完全托管的容器编排服务。它抽象化基础设施管理、支持自动扩展并确保高可用性，使其成为 Kubernetes 专业知识有限的团队的理想选择。

Amazon EKS provides multiple options for running Kubernetes workloads. By using EKS with Fargate profiles, you can deploy Kubernetes pods without managing any EC2 instances, as Fargate provides a serverless compute environment. This meets the company's goal of leveraging Kubernetes features while avoiding the operational overhead of managing compute infrastructure.

Amazon EKS 提供了运行 Kubernetes 工作负载的多种选项。通过将 EKS 与 Fargate 配置文件结合使用，您可以部署 Kubernetes Pod，而无需管理任何 EC2 实例，因为 Fargate 提供了无服务器计算环境。这满足了公司利用 Kubernetes 功能的目标，同时避免了管理计算基础设施的运营开销。

To automatically scale ECS tasks based on CPU utilization, you must enable Service Auto Scaling for the ECS service. This involves creating scaling policies that define when to add or remove tasks based on metrics like CPU utilization, which are collected by Amazon CloudWatch. Other options, such as manually scaling tasks or relying on an ALB or EC2 Auto Scaling, do not fulfill the requirement for automatic scaling of ECS tasks.

要根据 CPU 利用率自动伸缩 ECS 任务，您必须为 ECS 服务启用服务弹性伸缩。这涉及创建扩展策略，根据 Amazon CloudWatch 收集的 CPU 利用率等指标来定义何时添加或删除任务。其他选项（例如手动扩展任务或依赖 ALB 或 EC2 Auto Scaling）无法满足 ECS 任务自动扩展的要求。

When an Amazon RDS instance experiences high read traffic, read replicas are a cost-effective and scalable solution to offload read operations from the primary database. They allow read-heavy applications to distribute the query load across multiple replicas, improving performance without affecting write operations or requiring significant architectural changes. Other options like Multi-AZ deployment or scaling up the instance do not address the underlying issue of high read traffic as effectively.

当 Amazon RDS 实例经历高读取流量时，只读副本是一种经济高效且可扩展的解决方案，可以从主数据库卸载读取操作。它们允许读取密集型应用程序在多个副本之间分配查询负载，从而提高性能，而不会影响写入操作或需要重大的架构更改。其他选项（例如多可用区部署或扩展实例）无法有效解决高读取流量的根本问题。

Read replicas in Amazon RDS allow you to create read-only copies of your database, which can handle read traffic and offload it from the primary database. This is especially useful for applications that experience high read traffic, such as e-commerce platforms during peak sales events. By distributing the read workload across multiple replicas, you can improve overall database performance and scalability.

Amazon RDS 中的只读副本允许您创建数据库的只读副本，它可以处理读取流量并从主数据库卸载流量。这对于读取流量较高的应用程序尤其有用，例如销售高峰期间的电子商务平台。通过将读取工作负载分配到多个副本，您可以提高数据库的整体性能和可扩展性。

Read replicas in Amazon RDS are designed to handle high read traffic by offloading read operations from the primary database to replicas, improving application performance. This solution is effective without interrupting write operations on the primary database. Multi-AZ is for high availability and failover, not for scaling reads. While scaling up or migrating to DynamoDB could also be considered, they are less efficient or more complex than simply adding read replicas in this scenario.

Amazon RDS 中的只读副本旨在通过将读取操作从主数据库卸载到副本来处理高读取流量，从而提高应用程序性能。该方案在不中断主库写操作的情况下是有效的。多可用区用于高可用性和故障转移，而不是用于扩展读取。虽然也可以考虑扩展或迁移到 DynamoDB，但在这种情况下，它们比简单地添加只读副本效率更低或更复杂。

Read replicas are ideal for distributing read traffic and improving the performance of a database experiencing high read latency. They allow you to offload read queries from the primary instance to the replicas, which is a scalable and efficient solution for handling high read workloads. Other options like Multi-AZ are designed for failover, not performance, and scaling up the instance may not be cost-effective.

只读副本非常适合分配读取流量并提高经历高读取延迟的数据库的性能。它们允许您将读取查询从主实例卸载到副本，这是处理高读取工作负载的可扩展且高效的解决方案。其他选项（例如多可用区）是为故障转移而不是性能而设计的，并且扩展实例可能不具有成本效益。

AWS Step Functions is designed specifically for workflow orchestration, allowing you to define and execute workflows with built-in error handling, retries, and rollback. It is the best choice for this scenario where sequential execution and failure handling are required. Other options like AWS Lambda, Amazon SQS, and Amazon SWF either lack orchestration capabilities or are less suited to modern serverless architectures.

AWS Step Functions 专为工作流编排而设计，允许您定义和执行具有内置错误处理、重试和回滚功能的工作流。对于这种需要顺序执行和失败处理的场景来说，它是最佳选择。其他选项（例如 AWS Lambda、Amazon SQS 和 Amazon SWF）要么缺乏编排功能，要么不太适合现代无服务器架构。

AWS Step Functions is the most suitable service for orchestrating the described workflow, as it allows for sequential execution of tasks with built-in error handling and logging. It is specifically designed to manage workflows with complex dependencies, which is essential for the e-commerce platform's requirements. Other services like Amazon SNS, SQS, or S3 Event Notifications lack the ability to orchestrate workflows or handle sequential task execution.

AWS Step Functions 是编排所描述的工作流程的最合适的服务，因为它允许通过内置错误处理和日志记录来顺序执行任务。它专门设计用于管理具有复杂依赖关系的工作流程，这对于电子商务平台的要求至关重要。其他服务（例如 Amazon SNS、SQS 或 S3 事件通知）缺乏编排工作流程或处理顺序任务执行的能力。

AWS Step Functions is the ideal service for orchestrating a serverless workflow involving multiple steps, such as image processing in this scenario. It allows developers to define state machines that represent the workflow, manage task dependencies, and implement error handling and retries. This makes it a better option than alternatives like Amazon MQ, SWF, or EventBridge for this use case.

AWS Step Functions 是编排涉及多个步骤的无服务器工作流程的理想服务，例如本场景中的图像处理。它允许开发人员定义表示工作流的状态机、管理任务依赖性以及实现错误处理和重试。对于此用例，这使其成为比 Amazon MQ、SWF 或 EventBridge 等替代品更好的选择。

AWS Step Functions is the best choice for orchestrating workflows that involve multiple tasks (such as Lambda functions) in a sequence. It provides built-in capabilities for error handling, retries, and state management, reducing the need for custom code. Other options like SQS or EventBridge are not designed for sequential workflows, and writing custom orchestration code increases complexity unnecessarily.

AWS Step Functions 是编排涉及序列中多个任务（例如 Lambda 函数）的工作流程的最佳选择。它提供了内置的错误处理、重试和状态管理功能，减少了对自定义代码的需求。 SQS 或 EventBridge 等其他选项并非专为顺序工作流程而设计，编写自定义编排代码会不必要地增加复杂性。

To design a highly available and fault-tolerant architecture, the EC2 instances must be deployed across multiple Availability Zones to avoid a single point of failure. Auto Scaling ensures that there are always instances available in each AZ, and enabling Cross-Zone Load Balancing on the ALB ensures even traffic distribution across all AZs. These combined strategies provide high availability and fault tolerance for the application.

为了设计高可用和容错的架构，EC2 实例必须跨多个可用区部署，以避免单点故障。 Auto Scaling 可确保每个 AZ 中始终有可用的实例，并且在 ALB 上启用跨可用区负载均衡可确保所有 AZ 之间的流量均匀分配。这些组合策略为应用程序提供了高可用性和容错能力。

To design a highly available and fault-tolerant architecture, EC2 instances should be deployed across multiple Availability Zones to mitigate the impact of an AZ failure. An Auto Scaling group ensures that EC2 instances are dynamically managed based on demand, while enabling cross-zone load balancing on the ALB ensures even traffic distribution across all AZs. These changes together enhance the architecture's resilience and availability.

为了设计高可用和容错的架构，EC2 实例应该跨多个可用区部署，以减轻可用区故障的影响。 Auto Scaling 组可确保根据需求动态管理 EC2 实例，同时在 ALB 上启用跨区域负载均衡，确保流量在所有可用区之间均匀分配。这些变化共同增强了架构的弹性和可用性。

To design a highly available and fault-tolerant architecture, you need to minimize single points of failure. Adding a second Availability Zone to the load balancer’s target group ensures redundancy in case of an Availability Zone failure, while enabling Auto Scaling across multiple Availability Zones ensures the application can dynamically adjust to traffic demands and remain available. These changes together enhance fault tolerance and high availability for the web application.

要设计高可用性和容错架构，您需要最大限度地减少单点故障。向负载均衡器的目标组添加第二个可用区可确保在可用区发生故障时提供冗余，同时跨多个可用区启用自动缩放可确保应用程序可以动态调整流量需求并保持可用。这些更改共同增强了 Web 应用程序的容错能力和高可用性。

To design a highly available and fault-tolerant architecture, the web and application tiers should be distributed across multiple Availability Zones using Auto Scaling groups, and an Elastic Load Balancer should distribute traffic across these zones. The database tier should use Amazon RDS Multi-AZ deployments to ensure data consistency and availability. Additionally, stateless architectures for the web and application tiers can be achieved by storing session state in Amazon S3 or other external storage solutions.

要设计高可用性和容错架构，Web 和应用程序层应使用 Auto Scaling 组分布在多个可用区，并且 Elastic Load Balancer 应在这些区域之间分配流量。数据库层应采用 Amazon RDS 多可用区部署，以保证数据的一致性和可用性。此外，通过将会话状态存储在 Amazon S3 或其他外部存储解决方案中，可以实现 Web 和应用程序层的无状态架构。

The correct solution is to use AWS WAF to block requests with a Content-Length header indicating a file size larger than 100 MB. AWS WAF integrates with the ALB and can inspect HTTP requests for specific patterns, including header values. This approach prevents large file uploads from reaching the EC2 instances, preserving application performance without introducing unnecessary complexity.

正确的解决方案是使用 AWS WAF 来阻止 Content-Length 标头指示文件大小大于 100 MB 的请求。 AWS WAF 与 ALB 集成，可以检查 HTTP 请求的特定模式，包括标头值。这种方法可以防止大文件上传到达 EC2 实例，从而保持应用程序性能，而不会引入不必要的复杂性。

To handle high traffic efficiently and ensure cost optimization, the recommended approach is to use Auto Scaling for EC2 instances, enable Multi-AZ for fault tolerance in RDS, offload static content to Amazon S3, and utilize Read Replicas for read-intensive queries. Manually provisioning EC2 instances is not cost-effective or scalable and does not align with AWS best practices.

为了有效处理高流量并确保成本优化，建议的方法是对 EC2 实例使用 Auto Scaling，在 RDS 中启用多可用区容错，将静态内容卸载到 Amazon S3，并利用只读副本进行读取密集型查询。手动配置 EC2 实例不具有成本效益或可扩展性，并且不符合 AWS 最佳实践。

Amazon S3 with Transfer Acceleration is the best choice for storing unstructured data such as images and videos. It provides high durability, virtually unlimited scalability, and low-latency access through Transfer Acceleration, which routes traffic through AWS Edge Locations. This makes it an ideal solution for applications requiring global performance and reliability.

具有传输加速功能的 Amazon S3 是存储图像和视频等非结构化数据的最佳选择。它通过传输加速（通过 AWS 边缘站点路由流量）提供高耐用性、几乎无限的可扩展性和低延迟访问。这使其成为需要全局性能和可靠性的应用程序的理想解决方案。

To improve read scalability for the RDS database, creating Read Replicas is the most appropriate solution. Read Replicas allow the read workload to be distributed across multiple database instances, reducing the burden on the primary database instance. This approach is commonly used to handle increased read traffic and is supported by Amazon RDS for PostgreSQL.

为了提高 RDS 数据库的读扩展性，创建只读副本是最合适的解决方案。只读副本允许将读取工作负载分布在多个数据库实例上，从而减轻主数据库实例的负担。此方法通常用于处理增加的读取流量，并受 Amazon RDS for PostgreSQL 支持。

To implement a disaster recovery strategy using AWS global infrastructure, you need to deploy resources in a secondary AWS Region, use Amazon Route 53 to manage failover routing, and ensure data synchronization between Regions (e.g., with Cross-Region Read Replicas for RDS). These actions together enable minimal downtime and data consistency during a Region-wide failure.

要使用 AWS 全球基础设施实施灾难恢复策略，您需要在辅助 AWS 区域中部署资源，使用 Amazon Route 53 管理故障转移路由，并确保区域之间的数据同步（例如，使用 RDS 的跨区域只读副本）。这些操作共同实现了区域范围内故障期间最短的停机时间和数据一致性。

To meet the requirements for global traffic routing and failover across AWS Regions, Amazon Route 53 latency-based routing is ideal as it routes users to the nearest Region with low latency. Additionally, deploying the application in multiple AWS Regions ensures high availability and resilience in the event of a Region failure. Other options either do not meet the global traffic routing requirement or are designed for different use cases.

为了满足跨 AWS 区域的全球流量路由和故障转移的要求，Amazon Route 53 基于延迟的路由是理想的选择，因为它将用户以低延迟路由到最近的区域。此外，在多个 AWS 区域中部署应用程序可确保在区域发生故障时的高可用性和恢复能力。其他选项要么不满足全局流量路由要求，要么是针对不同的用例而设计的。

The Geolocation routing policy in Amazon Route 53 is specifically designed to route traffic based on the geographic location of the user. In this scenario, the company needs to direct users to the nearest AWS Region based on their location, making the Geolocation routing policy the correct answer. Other routing policies like Simple, Latency, and Weighted do not fulfill this requirement.

Amazon Route 53 中的 Geolocation 路由策略专门设计用于根据用户的地理位置路由流量。在这种情况下，公司需要根据用户的位置将用户引导到最近的 AWS 区域，从而使地理位置路由策略成为正确的答案。其他路由策略（例如简单、延迟和加权）无法满足此要求。

To meet the requirements of low latency for global users and disaster recovery across AWS Regions, the application should be deployed in multiple AWS Regions. Amazon Route 53 with latency-based routing ensures users are directed to the closest Region with the best performance, while failover routing provides high availability in case an entire Region becomes unavailable. These configurations work together to fulfill both the performance and availability needs of the application.

为了满足全球用户低延迟和跨 AWS 区域灾难恢复的要求，应用程序应该部署在多个 AWS 区域。 Amazon Route 53 具有基于延迟的路由，可确保用户被定向到具有最佳性能的最近区域，而故障转移路由则在整个区域不可用时提供高可用性。这些配置协同工作以满足应用程序的性能和可用性需求。

Amazon Comprehend is a fully managed natural language processing (NLP) service that enables you to derive insights from text. It can perform tasks such as sentiment analysis, key phrase detection, and language identification, which are directly applicable to analyzing customer feedback. Other services like Amazon Polly, Amazon Rekognition, and Amazon Translate have different use cases unrelated to this scenario.

Amazon Comprehend 是一项完全托管的自然语言处理 (NLP) 服务，使您能够从文本中获取见解。它可以执行情感分析、关键短语检测和语言识别等任务，这些任务直接适用于分析客户反馈。 Amazon Polly、Amazon Rekognition 和 Amazon Translate 等其他服务具有与此场景无关的不同用例。

To analyze customer feedback sentiment, Amazon Comprehend is the appropriate managed service, as it specializes in natural language processing tasks such as sentiment analysis. To convert the analyzed feedback into audio, Amazon Polly is the correct choice, as it provides text-to-speech capabilities. These two services together meet the requirements of the scenario effectively.

要分析客户反馈情绪，Amazon Comprehend 是合适的托管服务，因为它专门从事情绪分析等自然语言处理任务。要将分析后的反馈转换为音频，Amazon Polly 是正确的选择，因为它提供文本转语音功能。这两项服务共同有效满足了场景的需求。

Amazon Comprehend is ideal for analyzing text to extract topics and sentiment, fulfilling the requirement to analyze customer support emails. Amazon Polly is suitable for converting text into speech, enabling the company to provide audio responses for visually impaired users. Together, these services address the scenario's requirements effectively, while the other options do not align with the specific use case.

Amazon Comprehend 非常适合分析文本以提取主题和情绪，满足分析客户支持电子邮件的要求。 Amazon Polly 适合将文本转换为语音，使该公司能够为视障用户提供音频响应。这些服务共同有效地满足了场景的要求，而其他选项则与特定用例不相符。

Amazon Polly is the most appropriate service for converting text into audio content. It provides lifelike speech synthesis with a variety of customizable voices, making it an excellent choice for creating audio versions of written content. The other services (Amazon Transcribe, Amazon Comprehend, and Amazon Lex) do not offer the required text-to-speech functionality.

Amazon Polly 是将文本转换为音频内容的最合适的服务。它提供逼真的语音合成和各种可定制的声音，使其成为创建书面内容的音频版本的绝佳选择。其他服务（Amazon Transcribe、Amazon Comprehend 和 Amazon Lex）不提供所需的文本转语音功能。

In this scenario, the EC2 instance in the private subnet only needs to communicate with the ALB, which resides within the same VPC. The correct route table configuration includes a route to the local VPC CIDR block, allowing internal communication while ensuring that the private subnet does not have internet access. The other options either introduce unnecessary routes or violate the requirement to restrict internet access.

在此场景中，私有子网中的 EC2 实例仅需要与驻留在同一 VPC 内的 ALB 进行通信。正确的路由表配置包括到本地 VPC CIDR 块的路由，允许内部通信，同时确保私有子网无法访问 Internet。其他选项要么引入不必要的路由，要么违反限制互联网访问的要求。

To implement the described architecture, the public subnets need internet access through an Internet Gateway, and the private subnets need internet access through a NAT Gateway. The route tables must be properly configured: the public subnets' route table requires a route to the Internet Gateway, and the private subnets' route table requires a route to the NAT Gateway. Additionally, an Internet Gateway must be attached to the VPC to enable internet access.

为了实现所描述的体系结构，公共子网需要通过 Internet 网关访问 Internet，而私有子网需要通过 NAT 网关访问 Internet。必须正确配置路由表：公有子网的路由表需要到 Internet 网关的路由，私有子网的路由表需要到 NAT 网关的路由。此外，必须将 Internet 网关连接到 VPC 才能访问 Internet。

Instances in a private subnet cannot access the internet directly. To enable internet access, a NAT Gateway must be deployed in a public subnet. Then, the private subnet’s route table must be updated to route internet traffic (0.0.0.0/0) through the NAT Gateway. This design ensures outbound internet access while maintaining the security of the private subnet.

私有子网中的实例无法直接访问 Internet。要启用 Internet 访问，必须在公有子网中部署 NAT 网关。然后，必须更新私有子网的路由表以通过 NAT 网关路由互联网流量 (0.0.0.0/0)。此设计可确保出站 Internet 访问，同时维护私有子网的安全。

To enable internet access for resources in a private subnet securely and cost-effectively, a NAT Gateway should be used. It allows outbound internet traffic from the private subnet while blocking any inbound internet traffic. This ensures the subnet remains private and secure while meeting the application's requirements.

为了安全且经济高效地实现私有子网中资源的 Internet 访问，应使用 NAT 网关。它允许来自私有子网的出站互联网流量，同时阻止任何入站互联网流量。这可确保子网保持私有和安全，同时满足应用程序的要求。

The company requires a disaster recovery strategy with very low RTO and RPO. Active-active failover meets these requirements by running fully operational environments in multiple regions, allowing for seamless failover and minimal downtime. Other strategies, such as backup and restore, pilot light, and warm standby, have higher recovery times or may not meet the stringent RPO and RTO requirements.

该公司需要 RTO 和 RPO 非常低的灾难恢复策略。双活故障转移通过在多个区域运行完全可操作的环境来满足这些要求，从而实现无缝故障转移并最大限度地减少停机时间。其他策略（例如备份和恢复、指示灯和热待机）的恢复时间较长，或者可能无法满足严格的 RPO 和 RTO 要求。

Active-Active Failover is the most appropriate disaster recovery strategy for scenarios requiring extremely low RTO and RPO values. By maintaining fully operational environments in multiple regions, the system can instantly route traffic to another region in case of a failure, ensuring minimal downtime and data loss. Other strategies like Backup and Restore, Pilot Light, and Warm Standby involve delays in scaling or restoring, making them unsuitable for such strict requirements.

双活故障转移是最适合需要极低 RTO 和 RPO 值的场景的灾难恢复策略。通过在多个区域维护完全运行的环境，系统可以在发生故障时立即将流量路由到另一个区域，从而确保最大限度地减少停机时间和数据丢失。其他策略（例如备份和恢复、指示灯和热待机）会导致扩展或恢复延迟，因此不适合如此严格的要求。

Active-Active Failover is the only strategy that can meet the strict RTO of less than 15 minutes and RPO of less than 5 minutes. By running fully operational instances in multiple regions, the solution ensures continuous availability and immediate failover with minimal data loss. Other strategies, like Backup and Restore, Pilot Light, and Warm Standby, are less costly but come with longer recovery times or higher potential data loss, making them unsuitable for this scenario.

双活故障转移是唯一能够满足小于 15 分钟的严格 RTO 和小于 5 分钟的 RPO 的策略。通过在多个区域运行完全可操作的实例，该解决方案可确保持续可用性和即时故障转移，同时将数据丢失降至最低。其他策略，如备份和恢复、指示灯和热待机，成本较低，但恢复时间较长或潜在的数据丢失较高，因此不适合这种情况。

Warm Standby is the most appropriate DR strategy in this scenario because it balances cost and recovery requirements. It maintains a scaled-down version of the system in the secondary Region, enabling quick failover to meet the 1-hour RTO and the 5-minute RPO. More basic strategies like Backup and Restore or Pilot Light would likely fail to meet the RTO, while Active-Active would add unnecessary complexity and cost.

在这种情况下，热备份是最合适的灾难恢复策略，因为它平衡了成本和恢复要求。在辅助 Region 中维护系统缩容版本，实现快速故障转移，满足 1 小时 RTO 和 5 分钟 RPO。备份和恢复或 Pilot Light 等更基本的策略可能无法满足 RTO，而主动-主动则会增加不必要的复杂性和成本。

The company needs to design a distributed system that ensures high availability, fault tolerance, and scalability. Using auto-scaling groups ensures the system can handle dynamic traffic loads, while decoupling components with a message queue improves fault tolerance. Storing session data in a distributed manner ensures consistency and availability across nodes. Tightly coupled architectures and single points of failure, such as a single master database, should be avoided in a distributed design.

公司需要设计一个分布式系统，确保高可用性、容错性和可扩展性。使用自动缩放组可确保系统能够处理动态流量负载，同时将组件与消息队列解耦可提高容错能力。以分布式方式存储会话数据可确保跨节点的一致性和可用性。在分布式设计中应避免紧密耦合的架构和单点故障，例如单个主数据库。

Distributed design patterns focus on scalability, fault tolerance, and decoupling. By using Amazon SQS, Amazon SNS, and AWS Step Functions, the microservices in the e-commerce application can communicate asynchronously, handle spikes in traffic efficiently, and remain loosely coupled. Synchronous API calls and shared databases are not recommended for distributed architectures as they introduce dependencies and potential failure points.

分布式设计模式注重可扩展性、容错性和解耦性。通过使用 Amazon SQS、Amazon SNS 和 AWS Step Functions，电子商务应用程序中的微服务可以异步通信、有效处理流量峰值并保持松散耦合。不建议将同步 API 调用和共享数据库用于分布式架构，因为它们会引入依赖性和潜在的故障点。

To build a highly available and scalable e-commerce application, it is essential to use distributed design patterns that promote decoupling and scalability. Amazon SQS and SNS enable loose coupling and scalable message-driven architectures, while EC2 Auto Scaling ensures horizontal scaling based on traffic. Avoid tightly coupled architectures or storing state locally, as these hinder scalability and fault tolerance.

要构建高度可用且可扩展的电子商务应用程序，必须使用促进解耦和可扩展性的分布式设计模式。 Amazon SQS 和 SNS 可实现松散耦合和可扩展的消息驱动架构，而 EC2 Auto Scaling 可确保基于流量的水平扩展。避免紧密耦合的架构或在本地存储状态，因为这些会阻碍可扩展性和容错能力。

A distributed design pattern using Amazon S3, SQS, and DynamoDB is well-suited for this scenario. Amazon S3 handles large file uploads and integrates seamlessly with other AWS services like Lambda for triggering processing actions. Amazon SQS ensures reliable message delivery, retries, and deduplication, making the system fault-tolerant and scalable. Amazon DynamoDB can store metadata about the video uploads and their processing statuses, ensuring the system can track progress effectively. This combination ensures that the distributed architecture meets the requirements for scalability, fault tolerance, and durability.

使用 Amazon S3、SQS 和 DynamoDB 的分布式设计模式非常适合此场景。 Amazon S3 处理大型文件上传，并与 Lambda 等其他 AWS 服务无缝集成，以触发处理操作。 Amazon SQS 确保可靠的消息传递、重试和重复数据删除，使系统具有容错性和可扩展性。 Amazon DynamoDB 可以存储有关视频上传及其处理状态的元数据，确保系统可以有效跟踪进度。这种组合确保了分布式架构满足可扩展性、容错性和持久性的要求。

To ensure high availability and minimal downtime during a Regional outage, a Route 53 failover routing policy is the most appropriate choice. This configuration allows Route 53 to monitor the health of the primary endpoint and automatically route traffic to the secondary endpoint if the primary becomes unhealthy. Other routing policies like geolocation, latency, or weighted routing focus on distributing traffic but do not inherently provide failover capabilities.

为了确保区域中断期间的高可用性和最短的停机时间，Route 53 故障转移路由策略是最合适的选择。此配置允许 Route 53 监控主要端点的运行状况，并在主要端点变得不健康时自动将流量路由到辅助端点。其他路由策略（例如地理位置、延迟或加权路由）侧重于分配流量，但本质上并不提供故障转移功能。

To achieve high availability and automatic failover for an Amazon RDS database, enabling Multi-AZ deployment is the recommended approach. This ensures that a standby instance is deployed in a different Availability Zone and automatically promoted if the primary instance becomes unavailable. Other options, such as read replicas, require manual intervention and are not designed for automatic failover scenarios.

为了实现 Amazon RDS 数据库的高可用性和自动故障转移，建议启用多可用区部署。这可确保备用实例部署在不同的可用区中，并在主实例不可用时自动升级。其他选项（例如只读副本）需要手动干预，并且不适用于自动故障转移场景。

To implement a failover strategy, Route 53 with failover routing ensures traffic is redirected to the backup Region when the primary Region becomes unavailable. An Auto Scaling group in the backup Region automatically provisions necessary resources during failover. Cross-Region Replication (CRR) for S3 ensures that application data is consistent and available in the backup Region. ELBs cannot redirect traffic between Regions, and an active-active configuration does not align with the active-passive failover requirement specified in the scenario.

为了实施故障转移策略，具有故障转移路由功能的 Route 53 可确保在主区域不可用时将流量重定向到备份区域。备份区域中的 Auto Scaling 组会在故障转移期间自动配置必要的资源。 S3 的跨区域复制 (CRR) 可确保应用程序数据在备份区域中一致且可用。 ELB 无法在区域之间重定向流量，并且主动-主动配置与场景中指定的主动-被动故障转移要求不符。

Failover strategies for a web application require deploying resources across multiple AWS Regions to ensure availability in case one Region becomes unavailable. Using Route 53 with failover routing and health checks is a common approach to detect Region outages and redirect traffic. Additionally, configuring a second ALB in another Region with Route 53 latency-based routing ensures that traffic can be dynamically routed based on both health and latency, providing a robust failover strategy. Solutions like Auto Scaling and Multi-AZ only enhance resilience within a single Region, and AWS Global Accelerator is not tailored specifically for failover scenarios.

Web 应用程序的故障转移策略需要跨多个 AWS 区域部署资源，以确保在一个区域不可用时可用。将 Route 53 与故障转移路由和运行状况检查结合使用是检测区域中断和重定向流量的常用方法。此外，在另一个区域中使用基于 Route 53 延迟的路由配置第二个 ALB 可确保可以根据运行状况和延迟动态路由流量，从而提供强大的故障转移策略。 Auto Scaling 和 Multi-AZ 等解决方案只能增强单个区域内的弹性，而 AWS Global Accelerator 并不是专门针对故障转移场景而定制的。

The principle of immutable infrastructure involves replacing infrastructure components (e.g., EC2 instances) with new ones rather than modifying existing instances. By creating a new Auto Scaling group with the updated version of the application and gradually redirecting traffic, you ensure consistency, minimize deployment risks, and align with the immutable infrastructure approach.

不可变基础设施的原则涉及用新的基础设施组件（例如 EC2 实例）替换基础设施组件，而不是修改现有实例。通过使用更新版本的应用程序创建新的 Auto Scaling 组并逐步重定向流量，您可以确保一致性、最大限度地降低部署风险并与不可变基础设施方法保持一致。

Immutable infrastructure emphasizes the replacement of resources (e.g., EC2 instances) with entirely new versions rather than modifying resources in place. This approach ensures consistency, reduces errors, and simplifies rollback. Building new instances using pre-configured AMIs and replacing old instances aligns with this principle.

不可变基础设施强调用全新版本替换资源（例如 EC2 实例），而不是就地修改资源。这种方法可确保一致性、减少错误并简化回滚。使用预配置的 AMI 构建新实例并替换旧实例符合这一原则。

Immutable infrastructure emphasizes creating new infrastructure with the desired state rather than modifying existing infrastructure. Using an Auto Scaling Group to replace old EC2 instances with new ones ensures that updates are implemented in line with this principle, avoiding configuration drift or unintended issues caused by modifying running instances.

不可变基础设施强调创建具有所需状态的新基础设施，而不是修改现有基础设施。使用 Auto Scaling 组用新实例替换旧 EC2 实例可确保按照此原则实施更新，避免因修改正在运行的实例而导致配置漂移或意外问题。

AWS Elastic Beanstalk with Immutable Deployment Policy is the most suitable choice for implementing an immutable infrastructure approach. This deployment strategy ensures that updates are deployed by creating a new environment and replacing the old one entirely, rather than modifying existing resources. This approach minimizes risks and ensures consistency across deployments.

具有不可变部署策略的 AWS Elastic Beanstalk 是实施不可变基础设施方法的最合适选择。这一部署策略确保通过创建新环境并完全替换旧环境来部署更新，而不是修改现有资源。这种方法可以最大限度地降低风险并确保部署之间的一致性。

To route requests to different target groups based on domain names like 'example.com' and 'api.example.com', you can use the Application Load Balancer's host-based routing feature. This allows the ALB to inspect the HTTP Host header and forward traffic to the appropriate target group based on the domain name.

要根据“example.com”和“api.example.com”等域名将请求路由到不同的目标组，您可以使用 Application Load Balancer 的基于主机的路由功能。这允许 ALB 检查 HTTP 主机标头并根据域名将流量转发到适当的目标组。

Cross-zone load balancing ensures that requests are evenly distributed across all registered targets, regardless of their Availability Zone. This feature helps prevent scenarios where some instances handle more traffic than others, as observed in this case. By enabling cross-zone load balancing on the ALB, the company can ensure better traffic distribution and reduce the load on individual EC2 instances.

跨区域负载平衡可确保请求均匀分布在所有注册目标上，无论其可用区如何。此功能有助于防止出现某些实例比其他实例处理更多流量的情况，如本例所示。通过在 ALB 上启用跨区域负载均衡，该公司可以确保更好的流量分配并减少各个 EC2 实例的负载。