Amazon AWS Certified Solutions Architect - Associate Exam Material: What Is An Accurate Description Of Redundancy?

Are you an aspiring cloud architect or an IT professional aiming for the Amazon AWS Certified Solutions Architect – Associate (SAA-C03) Certification? Do you need to understand how to design highly reliable, available, and fault-tolerant cloud solutions that stand up to failures? This comprehensive guide is tailored to help you grasp redundancy, a fundamental concept for building resilient systems in the cloud computing realm.

This article will answer your critical questions about redundancy in AWS:

• What is redundancy in cloud computing, and why is it so important?
• How do reliability and availability differ, and why do they matter for your business?
• What are the different types of redundancy, and when should you use them?
• How can you implement redundancy for compute, storage, databases, and networks using AWS services?
• What are the key AWS services that enable redundancy, and how do they relate to the SAA-C03 exam?

We'll provide an accurate and detailed description of redundancy, explore its practical implementations within AWS environments, and highlight its indispensable role in modern IT architecture. By mastering these concepts, you'll not only be well-prepared to excel in the SAA-C03 exam but also build a robust foundation for a successful career in cloud architecture. To help you along the way, Study4Pass offers valuable resources for effective exam preparation.

Understanding System Reliability and Availability in the Cloud

In cloud environments, where services are expected to be always on, system reliability and availability are paramount. Downtime can lead to significant financial losses, damage to reputation, and loss of customer trust.

• Reliability refers to a system’s ability to perform its intended function correctly and consistently over a specific period. It's about how often a system fails.
• Availability measures the percentage of time a system or application is accessible and operational for users. It's about how much of the time the system is ready for use.

Both reliability and availability are fundamental to delivering high-quality, uninterrupted services, especially for mission-critical applications in sectors like e-commerce, healthcare, and financial systems.

Redundancy is a cornerstone strategy for dramatically enhancing both reliability and availability. It involves duplicating critical components or entire systems to ensure continued operation even if primary components fail. In AWS, redundancy is baked into the design of many services, including Amazon EC2, S3, RDS, and DynamoDB, empowering architects to easily design fault-tolerant and highly available solutions. The AWS Certified Solutions Architect – Associate (SAA-C03) exam thoroughly tests candidates’ ability to implement redundancy in cloud architectures, making it a core topic for your certification success. Study4Pass provides comprehensive study materials to help you confidently understand and apply these crucial redundancy concepts.

Why Reliability and Availability Are Crucial for Your Business

Ensuring high reliability and availability isn't just a technical best practice; it's a fundamental business imperative:

• Business Continuity: Unexpected downtime directly disrupts operations, leading to lost revenue, decreased productivity, and significant damage to customer trust and brand reputation.
• Enhanced User Experience: High availability guarantees that your applications and data are consistently accessible, providing a seamless and positive experience for end-users and customers.
• Scalability Support: Redundant system designs naturally support increased demand by allowing traffic to be distributed across multiple resources, ensuring performance doesn't degrade as your workload grows.
• Compliance & Regulatory Adherence: Many industries, such as healthcare (HIPAA) and finance (PCI DSS), have strict regulatory requirements that mandate high availability and data accessibility for sensitive information. Redundancy helps meet these mandates.

This article will accurately define redundancy, explore its diverse implementations, and emphasize its indispensable role within AWS cloud architectures, directly aligning with the SAA-C03 exam objectives.

What Exactly Is Redundancy? (An Accurate Description)

Redundancy is the strategic duplication of critical system components, resources, or infrastructure with the sole purpose of ensuring continued operation in the event of a failure. Its core aim is to eliminate single points of failure (SPOFs) by providing backup systems or resources that can seamlessly take over when primary components become unavailable. Redundancy can be applied at various layers of an IT system: from individual hardware components (e.g., power supplies, network links) to software instances, data, or even entire data centers.

Key Characteristics of Redundant Systems

• Fault Tolerance: Redundant systems are designed to continue functioning correctly despite the failure of one or more of their individual components. This could include hardware crashes, software bugs, or network outages.
• Seamless Failover: When a primary component fails, backup components should activate automatically and quickly, ideally with minimal or no disruption to users or applications.
• Proactive Design Principle: Redundancy isn't an afterthought; it's a planned design strategy that anticipates potential failures rather than just reacting to them after they occur.
• Scalability Support: By distributing workload across duplicated resources, redundant systems are inherently better equipped to handle increased traffic loads and scale out effectively.

Common Types of Redundancy

Understanding these types is crucial for designing resilient architectures:

1. Active-Active Redundancy:

• Description: Multiple identical components or systems operate simultaneously, actively sharing the workload. If one component fails, the remaining active components simply continue processing the full load without interruption.
• Example: Deploying multiple Amazon EC2 instances behind an Elastic Load Balancer (ELB), all actively serving user requests.

2. Active-Passive Redundancy:

• Description: A primary component or system operates, while a standby (passive) component remains idle or in a low-power state, ready to activate only if the primary fails. This involves a failover process.
• Example: An Amazon RDS Multi-AZ deployment, where a primary database instance is replicated to a standby instance in a different Availability Zone that takes over upon failure.

3. N+1 Redundancy:

• Description: This principle means you provide one additional component beyond the minimum number required for operation. For instance, if your system needs one server to function, N+1 means you deploy two servers (1+1). If it needs N components, you deploy N+1.
• Example: Providing extra network links in a data center for immediate failover paths, or having an additional power supply unit (PSU) in a server.

Real-World Redundancy Example

Consider a typical web application hosted on AWS. Redundancy is achieved by deploying multiple Amazon EC2 instances across different Availability Zones (AZs) within an AWS Region. If one entire AZ experiences an outage (a rare but possible event), traffic is automatically redirected by an Elastic Load Balancer (ELB) to the healthy EC2 instances in the other AZ, ensuring uninterrupted service for users.

Relevance to AWS SAA-C03 Exam

The SAA-C03 exam requires candidates to deeply understand redundancy as a core principle of fault-tolerant architecture. You'll encounter questions that involve designing redundant systems using various AWS services or identifying potential single points of failure (SPOFs) in a given cloud architecture diagram.

How Redundancy is Achieved in AWS: Common Implementations

AWS provides a rich set of services and architectural patterns to implement redundancy at every layer of your application stack. Here are the most common implementations, focusing on AWS solutions:

1. Compute Redundancy (EC2, Auto Scaling, ELB)

• Implementation: Deploy multiple Amazon EC2 instances (your virtual servers) across different AWS Availability Zones (AZs) or even across multiple AWS Regions. An Elastic Load Balancer (ELB) manages and distributes incoming traffic to these instances.
• How It Works: The ELB continuously monitors the health of your EC2 instances. If an instance fails or an entire AZ becomes unavailable, the ELB automatically reroutes traffic to the healthy instances in other available AZs. AWS Auto Scaling can further enhance this by automatically launching new instances to replace unhealthy ones or to handle increased load.
• Example: A critical web application uses EC2 instances in us-east-1a and us-east-1b. If us-east-1a experiences an issue, the ELB immediately shifts all user traffic to the healthy instances in us-east-1b, ensuring continuous web service.
• Key AWS Services: Amazon EC2, Auto Scaling, Elastic Load Balancing (ELB), Amazon Route 53 (for DNS failover across regions/endpoints).

2. Storage Redundancy (S3, EBS Snapshots)

• Implementation: Utilize AWS services like Amazon S3 (Simple Storage Service) for highly durable and redundant object storage, and implement EBS (Elastic Block Store) snapshots for block storage redundancy.
• How It Works: Amazon S3 is designed for 11 nines (99.999999999%) durability by automatically replicating your data across at least three geographically separate facilities (AZs) within a Region. S3 Cross-Region Replication (CRR) can add further redundancy by asynchronously copying objects to a different AWS Region. For EBS volumes, regularly taking snapshots provides point-in-time backups that can be restored to new volumes, even in different AZs.
• Example: Critical company files, customer backups, and static website content are stored in Amazon S3. To meet disaster recovery requirements, S3 CRR is enabled to replicate these files to a bucket in a different AWS Region, ensuring data access even if an entire Region experiences a rare outage.
• Key AWS Services: Amazon S3, S3 Cross-Region Replication (CRR), Amazon EBS (with snapshots), Amazon EFS (regionally redundant file system).

3. Database Redundancy (RDS, Aurora, DynamoDB)

• Implementation: Configure managed database services like Amazon RDS (Relational Database Service) with Multi-AZ deployments or read replicas. For NoSQL databases, utilize Amazon Aurora's highly available architecture or DynamoDB's global tables.
• How It Works:

- RDS Multi-AZ: AWS automatically provisions and maintains a synchronous standby replica of your database in a different AZ. If the primary instance fails (or the AZ becomes unhealthy), AWS automatically performs a DNS failover to the standby instance, typically within minutes.

- RDS Read Replicas: These are asynchronous copies of your primary database that can be used to offload read traffic, reducing the load on the primary and improving scalability. While not a direct failover mechanism, they can be promoted to primary in a disaster scenario.

- Aurora: Aurora's architecture separates compute and storage, replicating data across three AZs and maintaining multiple copies of data for high durability and fast recovery.

- DynamoDB Global Tables: Provide automatic, multi-Region, active-active replication for your NoSQL tables.

• Example: An e-commerce platform relies on an Amazon RDS Multi-AZ PostgreSQL database. If the primary database instance in one AZ fails due to underlying hardware issues, the standby instance in another AZ seamlessly takes over, ensuring minimal disruption to customer transactions.
• Key AWS Services: Amazon RDS, Amazon Aurora, Amazon DynamoDB (especially Global Tables).

4. Network Redundancy (Route 53, Direct Connect, VPC)

• Implementation: Design your network architecture with multiple, independent network paths. This includes using multiple AWS Direct Connect connections, redundant VPN connections, or leveraging VPC peering across different AZs or VPCs.
• How It Works: By having diverse connection paths, traffic can be automatically rerouted if a primary link or network component fails. Amazon Route 53 DNS failover is crucial here, directing traffic to healthy endpoints based on health checks.
• Example: A hybrid cloud setup has a primary AWS Direct Connect link to their on-premises data center. For high availability, a redundant VPN connection is configured as a backup. If the Direct Connect link goes down, traffic automatically switches to the VPN, ensuring continuous access to AWS resources from on-premises.
• Key AWS Services: Amazon Route 53 (with health checks), AWS Direct Connect, AWS Site-to-Site VPN, Amazon VPC.

5. Data Center Redundancy (AWS Availability Zones & Regions)

• Implementation: The most fundamental way to achieve large-scale redundancy in AWS is by deploying your resources across multiple AWS Availability Zones (AZs) within a Region and, for even higher resilience or disaster recovery, across multiple AWS Regions.
• How It Works: AZs are distinct, isolated physical locations within an AWS Region, each with independent power, cooling, networking, and security. They are geographically separated enough to be insulated from failures in other AZs but close enough for low-latency interconnections. Deploying across AZs protects against single data center failures. Multi-Region setups provide the highest level of redundancy, protecting against entire regional outages (e.g., due to natural disasters or widespread service disruptions).
• Example: A global SaaS application ensures maximum uptime by deploying its core application components (EC2, RDS, S3) not only across multiple AZs within its primary Region (e.g., us-east-1) but also by replicating essential data and having a failover strategy to a secondary Region (e.g., eu-west-1). This ensures service continuity even during rare regional outages.
• Key AWS Services: AWS Regions, AWS Availability Zones, AWS Global Accelerator (for improved performance and traffic management across regions).

Practical Scenario: Redundancy in Action

Imagine a leading SaaS company hosting its critical web application on AWS. They employ a robust redundancy strategy:

• Compute: Amazon EC2 instances are deployed across two different Availability Zones, managed by an Elastic Load Balancer (ELB) for active-active traffic distribution.
• Storage: All user-generated content and product images are stored in Amazon S3, which inherently provides multi-AZ redundancy. Additionally, S3 Cross-Region Replication (CRR) is enabled to asynchronously copy critical data to another AWS Region for disaster recovery.
• Database: The core application database is deployed as an Amazon RDS Multi-AZ instance, ensuring a synchronously replicated standby in a separate AZ.

If one of the primary AZs experiences a rare outage, the ELB automatically reroutes all incoming web traffic to the healthy EC2 instances in the surviving AZ. Simultaneously, because S3 provides automatic data replication, user access to images and files remains uninterrupted. For the database, the RDS Multi-AZ setup seamlessly performs an automatic failover to the standby instance within minutes, ensuring continuous database operations and minimal impact on customer experience. This comprehensive approach exemplifies how redundancy safeguards business continuity.

Key Considerations for Designing Redundant Architectures

When implementing redundancy, solutions architects must balance several factors:

• Cost vs. Availability: Redundancy inherently increases costs (e.g., running multiple EC2 instances, increased data transfer). Architects must carefully weigh the cost of downtime against the investment in redundancy to meet specific Recovery Time Objectives (RTO) and Recovery Point Objectives (RPO).
• Latency: While active-active setups generally minimize latency by distributing load, active-passive failover mechanisms can introduce a short delay during the transition period.
• Automation: Leveraging AWS tools like Auto Scaling, Route 53, and AWS CloudFormation is crucial for automating failover and recovery processes, significantly enhancing the efficiency and reliability of redundant systems.

Why Redundancy is Essential in Modern IT (Especially Cloud Environments)

Redundancy is more than just a feature; it's a foundational pillar of modern IT infrastructure, especially within dynamic cloud environments like AWS, where high availability and fault tolerance directly translate into business success.

1. Minimizing Costly Downtime

• Impact: Downtime is incredibly expensive. Industry reports, such as one by Gartner (2020), have estimated the average cost of IT downtime at $5,600 per minute, or over $300,000 per hour, for many businesses.
• Role of Redundancy: By providing backup resources and automated failover mechanisms, redundant systems ensure that when a failure occurs, the impact is minimized, or even eliminated, leading to significant cost savings.
• Example: If a primary web server fails, AWS Route 53 DNS failover can automatically redirect traffic to a healthy backup server in another Region, ensuring continuous uptime and preventing lost revenue.

2. Enhancing System Reliability

• Impact: Reliable systems build strong customer trust, support consistent application performance, and contribute directly to customer satisfaction and loyalty.
• Role of Redundancy: Redundancy is designed to eliminate Single Points of Failure (SPOFs). By duplicating critical components, the system as a whole remains operational even if individual parts fail, significantly improving overall system reliability.
• Example: Using Amazon RDS Multi-AZ ensures that your database remains highly reliable and available for critical applications, even if the underlying infrastructure of a primary AZ experiences an issue.

3. Supporting Seamless Scalability

• Impact: As user demand or data volumes grow, IT systems must be able to scale without compromising performance or stability.
• Role of Redundancy: Redundancy inherently supports scalability by enabling the distribution of workload across multiple, duplicated resources. This means the system can handle increased traffic without becoming congested.
• Example: AWS Auto Scaling groups, which launch new EC2 instances during traffic spikes, are a form of redundancy that ensures performance is maintained as the workload scales up.

4. Meeting Strict Compliance Requirements

• Impact: Many industries are subject to stringent regulations (e.g., GDPR, HIPAA, PCI DSS) that mandate high availability, data integrity, and swift data recovery for sensitive information.
• Role of Redundancy: Implementing robust redundancy strategies ensures continuous data access, data durability, and disaster recovery capabilities, which are essential for achieving and demonstrating compliance.
• Example: Amazon S3's multi-AZ replication and Cross-Region Replication ensure data durability and availability, helping organizations meet compliance standards for data retention and recovery.

5. Enabling Robust Disaster Recovery (DR)

• Impact: Catastrophic events such as natural disasters, widespread cyberattacks, or large-scale hardware failures can completely disrupt single-site operations.
• Role of Redundancy: Multi-Region deployments and comprehensive redundant architectures are the foundation for effective disaster recovery strategies, allowing for rapid recovery and restoration of services following widespread outages.
• Example: A multi-Region AWS architecture, with replicated data and standby environments, enables an organization to quickly restore its critical services after a major regional outage or disaster.

AWS-Specific Benefits for Redundancy

AWS offers unique advantages that simplify and enhance redundancy:

• Globally Distributed Infrastructure: AWS's vast network of Regions and Availability Zones provides built-in, geographically isolated infrastructure that forms the backbone for highly redundant deployments.
• Managed Services: Services like ELB, S3, RDS, Aurora, and DynamoDB handle much of the underlying complexity of redundancy for you, allowing architects to implement high availability with less operational overhead.
• Cost Optimization: AWS's pay-as-you-go pricing model and ability to scale resources on demand allow for more cost-effective redundancy configurations compared to traditional on-premises solutions where you might over-provision hardware.

Practical Scenario: E-commerce Platform Resiliency

Consider a popular e-commerce platform that hosts its entire website on AWS. To ensure maximum customer satisfaction and avoid lost sales, they prioritize redundancy:

• Their web servers run on Amazon EC2 instances deployed across multiple Availability Zones, distributing traffic via an Elastic Load Balancer (ELB).
• Product images and customer assets are stored in Amazon S3, utilizing its inherent multi-AZ durability and Cross-Region Replication (CRR) for offsite backup.
• Customer transaction data is managed by an Amazon RDS Multi-AZ database.

During a sudden surge in holiday traffic, the ELB efficiently distributes the load across all available EC2 instances, preventing any single server from becoming a bottleneck. Later, if a rare hardware failure impacts the primary database instance, the RDS Multi-AZ setup automatically fails over to the standby database in minutes, ensuring that customer transactions continue uninterrupted. This real-world example clearly demonstrates the power of a well-architected redundant system in AWS.

Relevance to AWS Certified Solutions Architect – Associate (SAA-C03) Exam

The AWS Certified Solutions Architect – Associate (SAA-C03) exam is designed to validate your ability to design robust, cost-effective, secure, and scalable solutions on the AWS platform. Redundancy is not just a single topic; it's a cross-cutting principle essential to multiple exam domains:

• Design Resilient Architectures (30% of exam): This is the core domain for redundancy. You'll be tested on implementing redundancy using Multi-AZ and Multi-Region deployments, Elastic Load Balancing (ELB), Auto Scaling groups, and Route 53 DNS failover.
• Design High-Performing Architectures (24% of exam): Leveraging redundancy is key to optimizing performance and eliminating Single Points of Failure (SPOFs) that could bottleneck your applications.
• Design Secure Architectures (20% of exam): Ensuring data redundancy with encrypted storage (e.g., S3, EBS) and secure failover mechanisms is critical for data protection and compliance.
• Design Cost-Optimized Architectures (20% of exam): While redundancy incurs costs, candidates must demonstrate the ability to balance these costs with the required availability levels and choose cost-effective redundancy strategies.
• Operational Excellence (6% of exam): This includes understanding how to automate redundancy, failover, and disaster recovery processes using tools like AWS CloudFormation.

Why Redundancy Matters for SAA-C03 Success

• Core Architecture Design Skill: Candidates must prove their ability to design fault-tolerant and highly available systems using a wide range of AWS services like EC2, S3, RDS, and DynamoDB.
• Troubleshooting & Problem Solving: Identifying Single Points of Failure (SPOFs) in existing or proposed architectures and recommending appropriate redundancy solutions are common exam scenarios.
• Adherence to Best Practices: Understanding and implementing redundancy aligns directly with the Reliability pillar of the AWS Well-Architected Framework, a crucial set of design principles for AWS solutions.
• Real-World Application: Proficiency in designing redundant solutions is a critical skill for any cloud architect building enterprise-grade, production-ready applications on AWS.

The SAA-C03 exam frequently includes practical, scenario-based questions about implementing redundancy. You might be asked to:

• Configure an Amazon RDS Multi-AZ database for high availability.
• Select the correct Elastic Load Balancer type for a highly available web application.
• Choose the appropriate S3 replication strategy for disaster recovery.
• Analyze an architectural diagram to identify its SPOFs and propose solutions.
• Recommend cost-effective redundancy strategies for a specific business requirement.

Study4Pass provides expertly targeted Practice Questions and realistic scenarios to reinforce these essential redundancy skills, ensuring you are thoroughly prepared for the exam.

Effective Study Tips for SAA-C03 Redundancy Concepts

To confidently ace the AWS Certified Solutions Architect – Associate (SAA-C03) exam and apply redundancy principles effectively, consider these key study tips:

• Deep Dive into AWS Service Redundancy Features: Go beyond surface-level knowledge. Systematically study the specific redundancy features within core AWS services:

- Amazon EC2: Understand Auto Scaling Groups, Elastic Load Balancers, and deploying instances across multiple AZs.

- Amazon S3: Focus on its 11 nines durability, Cross-Region Replication (CRR), and versioning.

- Amazon RDS & Aurora: Master Multi-AZ deployments, Read Replicas, and Aurora's unique high-availability architecture.

- Amazon Route 53: Learn about DNS failover, health checks, and routing policies.

- AWS Global Infrastructure: Understand the relationship between Regions and Availability Zones.

• Practice Architecture Design: Get hands-on! Use the AWS Management Console or AWS CloudFormation to build simple redundant architectures yourself. For instance, deploy a basic web application with EC2 instances in two AZs behind an ELB.
• Analyze and Simulate Exam Scenarios: Don't just memorize definitions. Actively analyze case studies and hypothetical scenarios involving failover, load balancing, data replication, and disaster recovery. Think about "what if" a component fails and how your redundant design handles it.
• Leverage Study4Pass Practice Tests: Use Study4Pass practice tests as a primary tool. They are designed to mirror the actual SAA-C03 exam, providing realistic questions and scenarios that will solidify your understanding of redundancy concepts and prepare you for the types of questions you'll encounter.

Final Thoughts: Redundancy – Your Blueprint for Resilient Cloud Solutions

Redundancy, defined as the strategic duplication of critical components to ensure continuous operation during failures, is undeniably the cornerstone of building reliable and available IT systems. Its intelligent implementation, utilizing strategies like Active-Active, Active-Passive, and N+1, effectively eliminates Single Points of Failure (SPOFs), supports scalability, ensures regulatory compliance, and forms the bedrock of robust disaster recovery plans.

In AWS environments, redundancy is not just a concept but a tangible reality, seamlessly achieved through the thoughtful use of services such as Multi-AZ EC2 deployments with ELB, Amazon S3's inherent replication and Cross-Region Replication, and Amazon RDS Multi-AZ failover. By mastering these principles and their practical application, candidates for the AWS Certified Solutions Architect – Associate (SAA-C03) exam gain the essential skills needed to design high-performance, fault-tolerant, and resilient cloud solutions that meet demanding business and regulatory requirements.

To make your exam preparation accessible and highly effective, Study4Pass stands out as a recommended resource. Their practice test PDF, competitively priced at just $19.99 USD, offers realistic questions and scenarios specifically designed to reinforce your understanding of redundancy concepts and other critical SAA-C03 topics. By combining this valuable theoretical knowledge with hands-on practice, you can confidently approach the SAA-C03 certification and build a strong, successful foundation for a thriving career as a cloud architect.

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Actual Questions From Amazon AWS Certified Solutions Architect - Associate SAA-C03 Certification Exam

Test your knowledge of redundancy for the SAA-C03 exam:

Which of the following statements provides the most accurate description of redundancy in the context of designing resilient AWS architectures?

A. Encrypting all sensitive data to ensure its confidentiality and privacy.

B. Duplicating critical system components, resources, or infrastructure to eliminate single points of failure and ensure continued operation during outages.

C. Optimizing cloud costs by implementing serverless computing and reducing overall resource usage.

D. Automating software deployments and infrastructure provisioning using Continuous Integration/Continuous Delivery (CI/CD) pipelines.

A Solutions Architect needs to design a highly durable storage solution for static website assets that automatically provides redundancy across multiple geographically distinct data centers (Availability Zones). Which AWS service is best suited for this requirement?

A. Amazon EC2

B. Amazon S3

C. AWS Lambda

D. Amazon VPC

A company running a critical e-commerce platform on AWS wants to ensure their relational database remains highly available and can automatically recover from an Availability Zone failure with minimal downtime. Which Amazon RDS feature provides this level of database redundancy?

A. Read Replicas

B. Multi-AZ Deployment

C. Cross-Region Replication

D. Automated Backups to S3

How does an Elastic Load Balancer (ELB) primarily contribute to enhancing redundancy and high availability in a typical AWS architecture for a web application?

A. It encrypts sensitive data in transit between clients and EC2 instances.

B. It automatically distributes incoming application traffic across multiple healthy EC2 instances, often spanning different Availability Zones, and seamlessly reroutes traffic away from unhealthy instances.

C. It stores large amounts of application data with extremely high durability.

D. It automates the deployment of new code versions to EC2 instances.

A solutions architect is designing a multi-Region architecture to ensure robust disaster recovery capabilities for a global application. Which AWS service would be used to perform DNS-based failover, directing user traffic to a healthy secondary Region if the primary Region experiences a widespread outage?

A. Amazon CloudWatch

B. AWS Direct Connect

C. Amazon Route 53

D. AWS CloudFormation