Amazon AWS Certified Advanced Networking — Specialty ANS-C01 Exam Dumps and Practice Test Questions Set10 Q136-150
Visit here for our full Amazon AWS Certified Advanced Networking — Specialty ANS-C01 exam dumps and practice test questions.
Question 136:
A company is deploying a hybrid cloud architecture that requires consistent network performance between their on-premises data center and AWS. They need to establish a dedicated connection with predictable network performance and reduced bandwidth costs. The connection must support both private and public AWS services. Which AWS service should the network architect implement to meet these requirements?
A) AWS Site-to-Site VPN with multiple tunnels for redundancy
B) AWS Direct Connect with a private virtual interface and a public virtual interface
C) AWS Transit Gateway with VPN attachments to the on-premises network
D) AWS PrivateLink endpoints for all required AWS services
Answer: B
Explanation:
AWS Direct Connect is the optimal solution for establishing a dedicated network connection between an on-premises data center and AWS. This service provides a private, dedicated connection that bypasses the public internet, offering consistent network performance, reduced bandwidth costs, and enhanced security. The question specifically emphasizes the need for predictable network performance and cost reduction, which are key benefits of Direct Connect.
When implementing Direct Connect, organizations can create multiple types of virtual interfaces to access different AWS resources. A private virtual interface allows connectivity to resources within a Virtual Private Cloud using private IP addresses, enabling secure communication with EC2 instances, RDS databases, and other VPC resources. Simultaneously, a public virtual interface provides access to AWS public services such as S3, DynamoDB, and other services that use public IP addresses. This dual-interface approach satisfies the requirement to support both private and public AWS services mentioned in the question.
The dedicated nature of Direct Connect connections provides bandwidth options ranging from 1 Gbps to 100 Gbps, with consistent performance characteristics. Unlike internet-based connections, Direct Connect offers predictable latency and throughput, making it ideal for applications requiring reliable network performance. Additionally, data transfer costs over Direct Connect are typically lower than standard data transfer rates over the internet, particularly for large-scale data migrations or applications with high bandwidth requirements.
Option A is incorrect because while Site-to-Site VPN provides encrypted connectivity over the internet, it does not offer the same level of predictable performance or cost benefits as Direct Connect. VPN connections are subject to internet variability and congestion, making them less suitable for applications requiring consistent performance.
Option C is incorrect because Transit Gateway with VPN attachments still relies on internet-based VPN connections, which do not provide the dedicated bandwidth and predictable performance that Direct Connect offers. While Transit Gateway simplifies network architecture, it doesn’t address the core requirement for dedicated connectivity.
Option D is incorrect because PrivateLink endpoints are designed for accessing specific AWS services privately from within a VPC, but they don’t provide a comprehensive solution for hybrid cloud connectivity or access to public AWS services from on-premises environments.
Question 137:
A network engineer is designing a multi-region AWS architecture for a global application. The application requires low-latency communication between VPCs in different regions and must support transitive routing between all connected networks. The solution should minimize operational overhead and provide centralized management. Which AWS networking solution best meets these requirements?
A) VPC peering connections between all VPCs in different regions
B) AWS Transit Gateway with inter-region peering attachments
C) AWS Direct Connect Gateway connecting all regional VPCs
D) Multiple Site-to-Site VPN connections between regional VPCs
Answer: B
Explanation:
AWS Transit Gateway with inter-region peering attachments is the ideal solution for creating a global network architecture that supports transitive routing and centralized management. Transit Gateway acts as a cloud router that connects VPCs, on-premises networks, and other Transit Gateways across different regions. The key advantage of this approach is its support for transitive routing, which allows networks connected to the Transit Gateway to communicate with each other without requiring direct connections between every pair of networks.
Inter-region peering enables Transit Gateways in different AWS regions to communicate with each other, creating a global network backbone. This capability is essential for applications requiring low-latency communication across regions. When you establish inter-region peering between Transit Gateways, traffic between VPCs in different regions flows through the AWS global network infrastructure, which provides optimized routing and consistent performance. This is particularly beneficial for global applications that need to maintain high availability and performance across multiple geographic locations.
The centralized management aspect of Transit Gateway significantly reduces operational overhead. Instead of managing numerous individual connections between VPCs, network administrators can manage all connectivity through a single Transit Gateway in each region. This simplifies network configuration, monitoring, and troubleshooting. Additionally, Transit Gateway supports route propagation and allows you to attach multiple VPCs, VPN connections, and Direct Connect gateways to a single Transit Gateway, further consolidating network management.
Option A is incorrect because VPC peering does not support transitive routing. Each VPC peering connection only allows direct communication between two VPCs, meaning you would need to establish a full mesh of peering connections to enable communication between all VPCs. This approach becomes operationally complex and difficult to manage as the number of VPCs increases.
Option C is incorrect because Direct Connect Gateway is primarily designed for connecting on-premises networks to multiple VPCs across regions, not for inter-VPC communication. While it can facilitate some multi-region connectivity, it doesn’t provide the transitive routing capabilities needed for this scenario.
Option D is incorrect because managing multiple Site-to-Site VPN connections between regional VPCs would create significant operational overhead and complexity, contradicting the requirement for minimized operational burden.
Question 138:
A company needs to implement a solution that allows hundreds of VPCs across multiple AWS accounts to share a single egress point for internet traffic. The solution must provide centralized security controls, logging, and traffic inspection capabilities. All outbound traffic should be routed through security appliances before reaching the internet. What is the most efficient architecture to achieve this requirement?
A) Deploy NAT Gateways in each VPC and use security groups for traffic control
B) Implement AWS Transit Gateway with a centralized egress VPC containing security appliances
C) Use VPC peering to route all traffic through a single VPC with an Internet Gateway
D) Configure AWS Network Firewall in each individual VPC for inspection
Answer: B
Explanation:
Implementing AWS Transit Gateway with a centralized egress VPC containing security appliances is the most efficient and scalable solution for this scenario. This architecture pattern, often called a «hub-and-spoke» model, allows multiple VPCs (spokes) to route their internet-bound traffic through a central egress VPC (hub) where security appliances are deployed. Transit Gateway serves as the central routing hub that connects all VPCs and directs traffic according to configured route tables.
In this architecture, the centralized egress VPC contains security appliances such as next-generation firewalls, intrusion detection systems, and other network security tools. All outbound internet traffic from the connected VPCs is routed through Transit Gateway to this centralized VPC, where it passes through the security appliances for inspection before being forwarded to the internet through a NAT Gateway or Internet Gateway. This approach provides a single point of control for implementing security policies, conducting deep packet inspection, and logging all outbound traffic, regardless of which VPC or account originated the traffic.
The scalability of this solution is significant. Transit Gateway supports thousands of VPC attachments and can handle high throughput requirements. As new VPCs are added across different accounts, they simply attach to the Transit Gateway, and their route tables are configured to direct internet traffic through the centralized egress VPC. This eliminates the need to deploy and manage security appliances in every VPC, reducing both capital and operational expenses. Additionally, centralized logging and monitoring from the egress VPC simplify compliance reporting and security analysis.
Option A is incorrect because deploying NAT Gateways and relying on security groups in each VPC does not provide centralized traffic inspection or the ability to use advanced security appliances. Security groups operate at the instance level and cannot perform deep packet inspection or sophisticated threat detection.
Option C is incorrect because VPC peering does not support transitive routing, making it impossible to efficiently route traffic from hundreds of VPCs through a single central VPC. You would need to establish individual peering connections between each VPC and the central VPC, which becomes unmanageable at scale.
Option D is incorrect because deploying AWS Network Firewall in each individual VPC contradicts the requirement for centralized management and would significantly increase costs and operational complexity across hundreds of VPCs.
Question 139:
A financial services company requires a networking solution that provides isolation between different business units while allowing selective communication between specific resources. Each business unit operates in separate AWS accounts, and the company needs to share certain centralized services like directory services and logging infrastructure. The solution must maintain strong security boundaries and comply with regulatory requirements. Which combination of AWS services should be implemented?
A) AWS Organizations with Service Control Policies and VPC peering between accounts
B) AWS Resource Access Manager with Transit Gateway and separate route tables for each business unit
C) Cross-account IAM roles with VPC endpoints in each account
D) AWS PrivateLink endpoints with Network Load Balancers for shared services
Answer: B
Explanation:
AWS Resource Access Manager combined with Transit Gateway and separate route tables provides the most comprehensive solution for this multi-account scenario with selective resource sharing. AWS Resource Access Manager enables secure sharing of AWS resources across accounts within an organization, including Transit Gateway attachments. This allows the company to create a centralized Transit Gateway that can be shared with multiple accounts representing different business units, while maintaining the security and isolation boundaries required by regulatory compliance.
Transit Gateway serves as the central networking hub that connects VPCs across different accounts. The key to achieving selective communication between specific resources lies in the configuration of separate route tables for each business unit. Transit Gateway supports multiple route table associations, allowing fine-grained control over which networks can communicate with each other. For example, route tables can be configured so that Business Unit A’s VPC can access the centralized directory services VPC but cannot communicate with Business Unit B’s VPC. This provides the necessary isolation between business units while enabling access to shared services.
The combination of these services maintains strong security boundaries through network-level segmentation rather than relying solely on application-level controls. Each business unit’s VPC remains in its own AWS account, providing account-level isolation and separate billing. The Transit Gateway route tables act as a policy enforcement point, ensuring that traffic can only flow according to explicitly defined rules. This architecture also simplifies the addition of new business units or shared services, as they can be attached to the Transit Gateway with appropriate route table configurations without requiring changes to existing VPCs.
Option A is incorrect because while Organizations and Service Control Policies provide governance and permission boundaries at the account level, VPC peering does not support transitive routing and would require a complex mesh of peering connections to enable selective communication patterns. This approach becomes unmanageable with multiple business units and shared services.
Option C is incorrect because cross-account IAM roles address authorization for API calls and resource access, but they do not provide the network-level connectivity and isolation required for this scenario. VPC endpoints alone cannot facilitate communication between resources in different accounts.
Option D is incorrect because while PrivateLink is excellent for exposing specific services, it requires each shared service to be individually exposed through a Network Load Balancer and endpoint configuration in each consuming account. This approach lacks the centralized routing control and becomes complex when managing multiple shared services and business units.
Question 140:
A company is migrating a latency-sensitive trading application to AWS. The application requires sub-millisecond latency between compute instances and must maintain consistent network performance. The architecture needs to support high packet per second rates and minimize network jitter. Which combination of AWS features should be implemented to meet these performance requirements?
A) EC2 instances in a placement group with enhanced networking using Elastic Network Adapters
B) Cluster placement group with EC2 instances using Elastic Fabric Adapter and enhanced networking
C) EC2 instances across multiple Availability Zones with Elastic Network Interfaces
D) Auto Scaling group of EC2 instances with Application Load Balancer
Answer: B
Explanation:
A cluster placement group with EC2 instances using Elastic Fabric Adapter and enhanced networking provides the optimal configuration for achieving sub-millisecond latency and high-performance networking. Cluster placement groups are specifically designed to pack instances close together within a single Availability Zone, minimizing the physical distance between instances and reducing network latency. This physical proximity is critical for latency-sensitive applications like trading platforms where even microseconds can impact performance.
Elastic Fabric Adapter is a network device that can be attached to EC2 instances to accelerate High Performance Computing and machine learning applications. EFA provides all the functionality of an Elastic Network Adapter plus an additional OS-bypass capability that enables applications to communicate directly with the network hardware, bypassing the operating system kernel. This OS-bypass functionality significantly reduces latency and jitter while increasing throughput. For applications requiring sub-millisecond latency, EFA is essential because it eliminates the processing overhead associated with traditional TCP/IP networking.
Enhanced networking, enabled by default with EFA, provides higher bandwidth, higher packet per second performance, and consistently lower inter-instance latencies. Enhanced networking uses single root I/O virtualization to provide high-performance networking capabilities on supported instance types. This technology is crucial for trading applications that generate high packet rates and require predictable network performance. The combination of cluster placement, EFA, and enhanced networking creates a network environment that minimizes latency, reduces jitter, and maximizes throughput.
Option A is incorrect because while placement groups with enhanced networking and Elastic Network Adapters provide good performance, standard ENAs do not offer the OS-bypass capability of EFA, which is necessary for achieving sub-millisecond latency requirements. Trading applications with extremely stringent latency requirements benefit significantly from EFA’s direct hardware access.
Option C is incorrect because distributing instances across multiple Availability Zones introduces additional network latency due to the physical distance between data centers. While this configuration provides high availability, it contradicts the requirement for sub-millisecond latency between instances.
Option D is incorrect because Auto Scaling groups with Application Load Balancers are designed for scalability and availability rather than ultra-low latency performance. Load balancers introduce additional network hops and processing delay, which is unacceptable for latency-sensitive trading applications.
Question 141:
A healthcare organization needs to implement a secure method for multiple AWS accounts to access a centralized shared services VPC that contains compliance and audit logging infrastructure. The solution must ensure that traffic between accounts never traverses the public internet and should support automatic discovery of shared services. The organization wants to minimize the number of VPC peering connections and simplify network management. What is the most appropriate solution?
A) VPC peering connections between each account’s VPC and the shared services VPC
B) AWS Transit Gateway with route table associations for each account’s VPC
C) AWS PrivateLink with VPC endpoint services in the shared services VPC
D) Site-to-Site VPN connections between each account’s VPC and the shared services VPC
Answer: B
Explanation:
AWS Transit Gateway with route table associations is the most appropriate solution for connecting multiple AWS accounts to a centralized shared services VPC. Transit Gateway functions as a cloud-based router that simplifies network connectivity by eliminating the need for complex peering relationships between VPCs. Instead of creating individual peering connections between each account’s VPC and the shared services VPC, all VPCs attach to a single Transit Gateway, which handles routing between them. This hub-and-spoke model dramatically reduces the number of network connections that need to be managed.
Transit Gateway ensures that all traffic remains within the AWS network infrastructure and never traverses the public internet. When VPCs in different accounts attach to the same Transit Gateway, traffic flows through AWS’s private backbone network, providing the security and privacy required for healthcare data. The Transit Gateway can be shared across accounts using AWS Resource Access Manager, allowing different accounts to attach their VPCs while maintaining account-level security boundaries. This is particularly important for healthcare organizations that must comply with HIPAA and other regulatory requirements regarding data transmission.
The route table associations in Transit Gateway provide flexible and granular control over network traffic flow. Each VPC attachment can be associated with a specific route table that defines which other VPCs it can communicate with. For the shared services VPC containing compliance and audit logging infrastructure, you can configure route tables to allow all accounts’ VPCs to reach the shared services while potentially restricting direct communication between the accounts themselves. This provides the necessary connectivity to centralized services while maintaining isolation between different departments or business units.
Option A is incorrect because VPC peering, while functional, does not scale well as the number of accounts increases. With VPC peering, you would need to establish and manage individual peering connections between each account’s VPC and the shared services VPC. If you have ten accounts, you need ten peering connections, and the complexity grows linearly with each additional account.
Option C is incorrect because while PrivateLink provides secure, private connectivity to services, it requires each service in the shared services VPC to be individually exposed through a VPC endpoint service with a Network Load Balancer. This approach is more complex to implement for comprehensive access to multiple services and does not provide the automatic routing capabilities of Transit Gateway.
Option D is incorrect because Site-to-Site VPN connections are designed for connecting on-premises networks to AWS, not for inter-VPC communication within AWS. Using VPN connections between VPCs would introduce unnecessary complexity and encryption overhead for traffic that already remains within the AWS network.
Question 142:
A media company is designing a content delivery architecture that requires distributing large video files from an origin server in AWS to global users with minimal latency. The solution must include DDoS protection, SSL/TLS termination, and the ability to customize the content delivery behavior based on user location. The company also needs detailed access logs for analytics. Which AWS service combination should be implemented?
A) Amazon CloudFront with AWS WAF, custom SSL certificates, and S3 bucket for logging
B) Application Load Balancer with AWS Shield Advanced in multiple regions
C) Amazon S3 with Transfer Acceleration and bucket policies for access control
D) Global Accelerator with Network Load Balancers and VPC Flow Logs
Answer: A
Explanation:
Amazon CloudFront with AWS WAF, custom SSL certificates, and S3 bucket for logging provides the comprehensive solution required for global content delivery with security and customization capabilities. CloudFront is AWS’s Content Delivery Network service that distributes content through a global network of edge locations, bringing content closer to end users and significantly reducing latency. For a media company delivering large video files to global audiences, CloudFront’s caching capabilities at edge locations minimize the load on origin servers and provide fast, reliable content delivery regardless of user location.
AWS WAF integration with CloudFront provides DDoS protection and customizable web application firewall rules that can filter malicious traffic before it reaches the origin. CloudFront automatically includes protection against common DDoS attacks at the network and transport layers through AWS Shield Standard, which is included at no additional cost. For enhanced protection, AWS Shield Advanced can be added. The ability to attach custom SSL/TLS certificates to CloudFront distributions enables secure HTTPS delivery of content while maintaining brand identity through custom domain names.
CloudFront’s geographic and content-based routing capabilities allow the media company to customize content delivery behavior based on user location. CloudFront supports Lambda@Edge, which enables running code at edge locations to modify request and response behavior dynamically. This can be used to serve different content versions based on geographic location, implement A/B testing, or apply custom authentication logic. Additionally, CloudFront can log every request to an S3 bucket, providing detailed access logs that include information about viewer location, request timing, and cache behavior. These logs are invaluable for analytics, understanding viewer behavior, and optimizing content delivery strategies.
Option B is incorrect because Application Load Balancer is designed for distributing traffic to application targets within a single region, not for global content delivery. While you could deploy ALBs in multiple regions, this approach lacks the global edge network and caching capabilities that CloudFront provides, resulting in higher latency and increased data transfer costs.
Option C is incorrect because while S3 with Transfer Acceleration can speed up uploads to S3, it does not provide a comprehensive content delivery solution. Transfer Acceleration is optimized for accelerating uploads to S3 over long distances, not for delivering content to end users. S3 alone lacks the edge caching, DDoS protection, and content customization capabilities required.
Option D is incorrect because Global Accelerator is designed to improve availability and performance of applications by routing traffic through AWS’s global network to optimal endpoints. However, it does not provide content caching at edge locations like CloudFront does, making it less suitable for delivering large media files efficiently.
Question 143:
A network engineer is troubleshooting connectivity issues between two VPCs connected via VPC peering. The peering connection shows as active, but instances in VPC A cannot communicate with instances in VPC B. Security groups and network ACLs have been verified to allow the necessary traffic. What is the most likely cause of this connectivity issue?
A) The VPC CIDR blocks are overlapping between the two VPCs
B) The route tables in one or both VPCs are missing routes to the peered VPC CIDR block
C) The Internet Gateway is not properly configured in both VPCs
D) Enhanced networking is not enabled on the EC2 instances
Answer: B
Explanation:
The most likely cause of connectivity failure between peered VPCs when the peering connection is active and security configurations are correct is missing route table entries. VPC peering connections require explicit route table configuration in both VPCs to enable traffic flow. Even though a peering connection may show as active in the AWS console, this status only indicates that the peering relationship has been established successfully. It does not automatically configure the routes needed to direct traffic through the peering connection.
When you create a VPC peering connection, you must manually add routes to the route tables in each VPC that needs to communicate with the peered VPC. For example, if VPC A has a CIDR block of 10.0.0.0/16 and VPC B has a CIDR block of 10.1.0.0/16, the route table in VPC A must include a route with destination 10.1.0.0/16 pointing to the peering connection as the target. Similarly, the route table in VPC B must include a route with destination 10.0.0.0/16 pointing to the same peering connection. Without these routes, the VPC router does not know where to send traffic destined for the peered VPC, causing packets to be dropped.
This is a common oversight during VPC peering configuration, especially in environments with multiple route tables. Each subnet in a VPC can be associated with a different route table, so you must ensure that routes are added to all route tables that need to communicate with the peered VPC. If instances are in subnets associated with different route tables, and only some of those route tables have the peering routes configured, you may observe inconsistent connectivity where some instances can communicate while others cannot.
Option A is incorrect because if the VPC CIDR blocks were overlapping, AWS would not allow you to create the peering connection in the first place. VPC peering requires non-overlapping CIDR blocks, and this validation is enforced during the peering connection creation process. The question states that the peering connection shows as active, which confirms that the CIDR blocks do not overlap.
Option C is incorrect because Internet Gateways are not involved in VPC peering communication. Internet Gateways provide connectivity between VPC resources and the public internet, but VPC peering traffic flows directly between the peered VPCs through AWS’s internal network infrastructure without traversing the internet.
Option D is incorrect because enhanced networking is a feature that improves network performance by providing higher bandwidth and lower latency, but it is not a requirement for basic VPC peering connectivity. Instances without enhanced networking can still communicate through VPC peering connections, albeit with standard networking performance.
Question 144:
A company is implementing AWS Direct Connect to establish a dedicated connection between their on-premises data center and AWS. They require high availability and cannot tolerate any downtime due to connection failures. The network team needs to design a resilient solution that maintains connectivity even if an entire Direct Connect location fails. What is the most appropriate architecture to achieve this level of redundancy?
A) Single Direct Connect connection with a backup Site-to-Site VPN connection
B) Two Direct Connect connections terminating at the same Direct Connect location
C) Two Direct Connect connections terminating at different Direct Connect locations with separate routers
D) Multiple VPN connections to different AWS regions as primary connectivity
Answer: C
Explanation:
Two Direct Connect connections terminating at different Direct Connect locations with separate routers provides the highest level of redundancy and resilience for AWS Direct Connect connectivity. This architecture protects against multiple failure scenarios including connection failures, device failures, and entire location failures. Direct Connect locations are physical facilities where AWS’s network meets customer or carrier networks, and each location represents a potential single point of failure if not properly redundant.
By establishing connections at two different Direct Connect locations, you eliminate the risk of losing all connectivity if one location experiences an outage due to power failure, natural disaster, or other catastrophic events. This geographic diversity is critical for organizations that cannot tolerate any downtime. Additionally, using separate customer routers at the on-premises side for each connection ensures that a router failure does not impact both connections. This design follows AWS’s best practices for maximum resiliency and is essential for enterprise-grade implementations where availability is paramount.
The implementation involves establishing two separate Direct Connect connections, each from your on-premises location to a different Direct Connect location, and then from each Direct Connect location to your AWS Virtual Private Gateway or Direct Connect Gateway. The routing configuration should use BGP with appropriate route preferences to manage active/active or active/passive failover scenarios. In an active/active configuration, both connections carry traffic simultaneously, providing load distribution and immediate failover capability. The AWS Direct Connect Resiliency Toolkit helps design these highly available configurations.
Option A is incorrect because while a backup Site-to-Site VPN provides some level of redundancy, VPN connections traverse the public internet and are subject to internet reliability and performance variability. For organizations requiring enterprise-grade availability and consistent performance, relying on VPN as a backup introduces risk. Additionally, failover to VPN may result in significantly reduced bandwidth and increased latency.
Option B is incorrect because having two connections to the same Direct Connect location does not protect against location-level failures. If the Direct Connect location experiences an outage affecting its infrastructure, both connections would be impacted. This configuration provides redundancy only against individual connection or port failures, not against location-wide issues.
Option D is incorrect because VPN connections traverse the public internet and do not provide the same level of performance, reliability, or bandwidth as Direct Connect. Using VPN as the primary connectivity method contradicts the stated requirement for a dedicated connection and would not meet the availability standards expected for enterprise applications.
Question 145:
A SaaS company offers its application to multiple customers, each requiring network isolation and private connectivity to their own AWS resources. The company needs to enable customers to securely access the application without exposing it to the public internet, while maintaining complete separation between different customers’ network traffic. Which AWS service should be implemented to meet these requirements?
A) VPC peering connections between the company’s VPC and each customer’s VPC
B) AWS PrivateLink with VPC endpoint services for the application
C) Application Load Balancer with host-based routing for each customer
D) AWS Transit Gateway with separate route tables for each customer
Answer: B
Explanation:
AWS PrivateLink with VPC endpoint services is the ideal solution for providing secure, private access to a SaaS application while maintaining network isolation between customers. PrivateLink enables you to expose your application as a VPC endpoint service, which customers can then access through VPC endpoints created in their own VPCs. This architecture ensures that traffic between customers and the SaaS application never traverses the public internet, addressing the security requirement, while providing complete network separation between different customers.
When implementing PrivateLink, the SaaS company creates a Network Load Balancer in front of their application and configures it as a VPC endpoint service. Each customer creates a VPC endpoint in their own VPC that connects to this endpoint service. The critical aspect of this architecture is that each customer’s VPC endpoint establishes an independent, isolated connection to the service. The traffic from one customer never intermingles with traffic from another customer, and customers cannot see or reach each other’s networks. Each customer accesses the service through their own private IP addresses within their VPC, maintaining network isolation.
PrivateLink provides additional benefits beyond security and isolation. It scales automatically as more customers subscribe to the service, and each customer’s VPC endpoint is created independently without requiring changes to the SaaS provider’s infrastructure. The service also works across AWS accounts, making it perfect for multi-tenant SaaS architectures. Furthermore, PrivateLink supports granular access controls through endpoint policies, allowing the SaaS provider to implement customer-specific access restrictions. This architecture is commonly used by AWS itself for providing access to AWS services like S3 and DynamoDB through VPC endpoints.
Option A is incorrect because VPC peering creates a direct network connection between VPCs, which would allow customers to potentially access each other’s resources if not carefully managed with security groups and network ACLs. More importantly, VPC peering does not scale well for a SaaS model with many customers, as it requires individual peering connections and complex network configurations.
Option C is incorrect because an Application Load Balancer exposed through an Internet Gateway would not meet the requirement for private connectivity that avoids the public internet. While host-based routing can direct different customers to different targets, the traffic would still traverse the public internet, contradicting the security requirements.
Option D is incorrect because Transit Gateway is designed for connecting multiple VPCs and on-premises networks in a hub-and-spoke model, not for exposing services to external customers. While separate route tables provide isolation, this architecture would require customers’ VPCs to be connected to the company’s Transit Gateway, creating a shared infrastructure that is less secure and more complex than PrivateLink.
Question 146:
A company operates a latency-sensitive video streaming application that serves users across multiple AWS regions. They need to route users to the nearest healthy endpoint and provide fast failover if an endpoint becomes unavailable. The solution should work at the network layer and provide static IP addresses that can be whitelisted by corporate clients. Which AWS service should be implemented?
A) Amazon Route 53 with latency-based routing policies
B) AWS Global Accelerator with multiple endpoint groups in different regions
C) Amazon CloudFront with multiple origin servers in different regions
D) Application Load Balancer with cross-zone load balancing enabled
Answer: B
Explanation:
AWS Global Accelerator is the optimal solution for this scenario because it operates at the network layer and provides static anycast IP addresses that remain constant even as endpoints change. Global Accelerator uses the AWS global network infrastructure to route traffic from users to application endpoints in multiple regions, automatically directing users to the nearest healthy endpoint based on performance and health checks. The anycast IP addresses provided by Global Accelerator can be easily whitelisted by corporate clients, addressing one of the key requirements.
Global Accelerator continuously monitors the health of application endpoints using health checks and automatically routes traffic away from unhealthy endpoints to healthy ones in other regions. This failover happens in seconds, making it ideal for latency-sensitive applications that cannot tolerate extended downtime. Unlike DNS-based routing solutions, Global Accelerator’s failover does not rely on DNS TTL or client DNS caching, providing immediate traffic rerouting when failures occur. This is particularly important for video streaming applications where even brief interruptions can significantly impact user experience.
The service provides two static anycast IP addresses that serve as fixed entry points to your application hosted across multiple AWS regions. Traffic enters the AWS global network at the edge location closest to users and is then routed across AWS’s private network to the optimal endpoint. This reduces internet-related latency and jitter, providing more predictable performance for streaming applications. Global Accelerator’s traffic dials allow you to control the percentage of traffic directed to each endpoint group, enabling gradual traffic shifts for deployments or maintenance activities.
Option A is incorrect because while Route 53 with latency-based routing can direct users to the lowest-latency endpoint, DNS-based routing depends on DNS resolution and is subject to DNS caching by clients and intermediate resolvers. This means that when an endpoint fails, clients may continue to use cached DNS records pointing to the failed endpoint until the TTL expires, resulting in slower failover compared to Global Accelerator.
Option C is incorrect because CloudFront is a Content Delivery Network service optimized for caching and delivering static and dynamic content. While CloudFront has multiple origin servers capabilities and global edge locations, it does not provide static IP addresses that can be whitelisted, nor does it operate at the network layer in the same way Global Accelerator does for routing traffic to application endpoints.
Option D is incorrect because Application Load Balancer operates within a single region and does not provide multi-region routing capabilities. While cross-zone load balancing improves availability within a region, it does not address the requirement for routing users to the nearest endpoint across multiple regions.
Question 147:
A financial institution is implementing a network architecture that requires encrypting all traffic between VPCs across different AWS regions. The solution must provide encryption at the network layer and should not require changes to applications. The network team needs to verify encryption is active and must be able to rotate encryption keys regularly. What is the most appropriate solution?
A) VPC peering with application-level encryption using TLS
B) AWS Transit Gateway with inter-region peering and VPN attachments
C) Site-to-Site VPN connections between Virtual Private Gateways in each region
D) AWS Direct Connect with MACsec encryption enabled on the connection
Answer: B
Explanation:
AWS Transit Gateway with inter-region peering and VPN attachments provides network-layer encryption for traffic between VPCs across different regions while meeting all the specified requirements. When you establish a VPN attachment to Transit Gateway, all traffic flowing through that attachment is automatically encrypted using IPsec encryption. This encryption occurs at the network layer, which means applications do not need to be modified or aware of the encryption process. The encryption is handled transparently by the network infrastructure.
Transit Gateway inter-region peering connections themselves do not provide encryption, but by combining inter-region peering with VPN attachments, you can ensure that all traffic traversing between regions is encrypted. The architecture involves creating Transit Gateways in each region, establishing VPN connections to these Transit Gateways, and then creating inter-region peering between them. This setup ensures that traffic is encrypted as it travels through the VPN tunnels, providing the network-layer encryption required by the financial institution.
The VPN attachments to Transit Gateway use IPsec protocol with Internet Key Exchange for establishing secure tunnels. AWS manages the encryption keys used for these VPN connections, and the keys are automatically rotated according to IPsec standards. You can verify that encryption is active by monitoring VPN tunnel status and examining VPN tunnel metrics in CloudWatch. Additionally, VPN connections support configurable encryption algorithms including AES-256, meeting stringent security requirements for financial services. The solution scales efficiently as you can attach multiple VPCs to each Transit Gateway without creating a complex mesh of VPN connections.
Option A is incorrect because VPC peering itself does not provide encryption; traffic between peered VPCs travels over AWS’s internal network but is not encrypted by default. While you could implement application-level TLS encryption, this would require modifying applications, which contradicts the requirement that the solution should not require application changes.
Option C is incorrect because Site-to-Site VPN connections are designed for connecting on-premises networks to AWS, not for inter-VPC communication within AWS. While technically possible to create VPN connections between Virtual Private Gateways in different regions, this approach is complex, expensive, and not the intended use case for Site-to-Site VPN.
Option D is incorrect because MACsec encryption on Direct Connect provides encryption for traffic between on-premises locations and AWS over Direct Connect links, not for traffic between VPCs within AWS. Direct Connect is used for hybrid cloud connectivity, not for inter-region VPC communication.
Question 148:
A company is experiencing intermittent connectivity issues with their application deployed across multiple Availability Zones. Network logs show that some requests are timing out, while others complete successfully. The network team suspects that one of the Availability Zones may have degraded network performance. What is the most effective approach to diagnose and isolate the problematic Availability Zone?
A) Review VPC Flow Logs filtered by Availability Zone and analyze rejected connections
B) Enable VPC Traffic Mirroring to capture and analyze packet-level data from each Availability Zone
C) Create CloudWatch metrics for response times grouped by Availability Zone and compare performance
D) Disable each Availability Zone sequentially and monitor application performance
Answer: C
Explanation:
Creating CloudWatch metrics for response times grouped by Availability Zone is the most effective and least disruptive approach to diagnose network performance issues across Availability Zones. This method allows you to systematically measure and compare the performance characteristics of each Availability Zone over time, identifying patterns that indicate degraded performance in a specific zone. By instrumenting your application to emit custom CloudWatch metrics that include the Availability Zone as a dimension, you can create dashboards and alarms that highlight performance discrepancies between zones.
This diagnostic approach is proactive and continuous, providing ongoing visibility into per-zone performance without disrupting normal operations. You can configure your application or load balancers to record response times, connection establishment times, and request completion rates, all tagged with the Availability Zone information. CloudWatch’s statistical aggregation capabilities allow you to analyze percentiles such as p50, p95, and p99 latencies, which are particularly useful for identifying intermittent issues that affect only a subset of requests. If one Availability Zone consistently shows higher latencies or increased error rates, this clearly indicates a problem with that zone.
The metrics-based approach also enables you to correlate network performance with other system metrics such as CPU utilization, memory usage, and disk I/O, helping to determine whether the performance degradation is truly network-related or caused by other factors. Additionally, historical metric data allows you to identify whether the issue is new or has been gradually worsening over time. You can set up CloudWatch alarms to automatically notify the operations team when performance in any Availability Zone deviates significantly from the baseline, enabling rapid response to emerging issues.
Option A is incorrect because VPC Flow Logs primarily capture information about accepted and rejected traffic at the network interface level, but they do not provide timing information or performance metrics. Flow Logs can tell you whether packets were delivered but cannot diagnose performance degradation or measure latency, which are the key indicators of degraded network performance.
Option B is incorrect because VPC Traffic Mirroring, while valuable for deep packet inspection and security analysis, is complex to set up and generates large volumes of data that must be analyzed using specialized tools. This approach is more suitable for investigating specific security concerns or protocol-level issues rather than diagnosing general performance degradation across Availability Zones.
Option D is incorrect because disabling Availability Zones sequentially is highly disruptive to the application and defeats the purpose of multi-AZ deployment. This trial-and-error approach risks impacting customer experience and does not provide quantitative data about the nature or extent of the performance issue. It should only be considered as a last resort in critical situations.
Question 149:
A company needs to implement network segmentation for a multi-tier application deployed in a VPC. The application consists of web servers in public subnets, application servers in private subnets, and database servers in isolated subnets. The security team requires that database servers can only be accessed from application servers, and application servers can only be accessed from web servers. What combination of network controls should be implemented to enforce these requirements?
A) Security groups with stateful rules allowing traffic only from required source security groups
B) Network ACLs with stateless rules permitting traffic based on IP address ranges
C) Both security groups for instance-level control and network ACLs for subnet-level defense in depth
D) Route tables with custom routes directing traffic through a network firewall appliance
Answer: C
Explanation:
Implementing both security groups for instance-level control and network ACLs for subnet-level protection provides defense in depth, which is a security best practice for network segmentation. This dual-layer approach ensures that even if one security control is misconfigured or bypassed, the second layer provides an additional barrier to unauthorized access. Security groups operate at the instance level and are stateful, meaning they automatically allow return traffic for established connections, while network ACLs operate at the subnet level and are stateless, requiring explicit rules for both inbound and outbound traffic.
Security groups are the primary mechanism for controlling traffic to and from individual instances. For this multi-tier application, you would configure the database security group to only allow inbound traffic from the application server security group on the database port. Similarly, the application server security group would only allow inbound traffic from the web server security group on the application port. Security groups support referencing other security groups as sources, which is more maintainable than IP-based rules because it automatically adapts as instances are added or removed.
Network ACLs provide an additional layer of control at the subnet boundary. Even if an instance’s security group is misconfigured, the network ACL can block unauthorized traffic from reaching the subnet. For the database subnet, the network ACL would be configured to deny all traffic except that coming from the application server subnet’s IP range. This creates a defense-in-depth strategy where an attacker would need to bypass both the network ACL and the security group to gain unauthorized access. Network ACLs also allow you to implement explicit deny rules, which can be useful for blocking known malicious IP addresses.
Option A is incorrect because while security groups alone can effectively control traffic and are sufficient for basic segmentation, they represent a single layer of security. Best practices for highly sensitive applications, particularly those involving databases, recommend implementing multiple layers of security controls to reduce the risk of misconfiguration or compromise.
Option B is incorrect because relying solely on network ACLs with IP-based rules is less flexible and more difficult to maintain than using security groups with source security group references. As instances are launched or terminated, IP addresses change, requiring constant updates to network ACL rules. Additionally, network ACLs alone do not provide instance-level granularity.
Option D is incorrect because while routing traffic through a network firewall appliance can provide advanced inspection capabilities, it introduces additional complexity, cost, and potential performance bottlenecks. For standard network segmentation requirements like those described, security groups and network ACLs provide sufficient control without the overhead of dedicated firewall appliances.
Question 150:
A network administrator needs to troubleshoot DNS resolution issues for resources in a VPC. EC2 instances are unable to resolve public DNS names, but they can communicate with other instances in the VPC using IP addresses. The VPC has DNS resolution and DNS hostnames enabled. What is the most likely cause of this issue?
A) The VPC’s DHCP options set is configured with incorrect DNS servers
B) The security group attached to the instances is blocking DNS traffic on port 53
C) The route table does not have a route to the Internet Gateway
D) The network ACL is blocking outbound traffic on ephemeral ports
Answer: A
Explanation:
The most likely cause of DNS resolution failure for public DNS names while internal VPC communication works normally is an incorrectly configured DHCP options set. The DHCP options set in a VPC controls what DNS servers instances will use for DNS resolution. When you create a VPC, AWS automatically creates a default DHCP options set that specifies the Amazon-provided DNS server, which resides at the VPC base plus two IP address. For example, in a VPC with CIDR 10.0.0.0/16, the Amazon DNS server is at 10.0.0.2.
If a custom DHCP options set has been created and associated with the VPC, and it specifies incorrect DNS servers or on-premises DNS servers that are unreachable, instances will be unable to resolve public DNS names. The Amazon-provided DNS server is responsible for resolving both AWS internal DNS names and public internet DNS names. If instances are configured to use DNS servers that don’t have internet connectivity or are incorrectly configured, DNS resolution for public names will fail while IP-based communication within the VPC continues to work normally.
This scenario is particularly common in hybrid cloud environments where administrators create custom DHCP options sets to point instances to on-premises DNS servers for resolving internal corporate DNS names. If the on-premises DNS servers cannot be reached from the VPC due to connectivity issues, or if they are not configured to forward public DNS queries to internet DNS servers, public DNS resolution will fail. The fact that instances can communicate using IP addresses confirms that basic network connectivity is working, isolating the problem to DNS resolution specifically.
Option B is incorrect because security groups operate at the protocol and port level, not at the application level of DNS. Additionally, security groups are stateful, meaning if an instance initiates a DNS query outbound, the response is automatically allowed back. DNS traffic uses UDP port 53 primarily, and security groups don’t typically block outbound DNS traffic by default.
Option C is incorrect because while a missing route to an Internet Gateway would prevent instances from accessing the public internet, it would not specifically affect DNS resolution only. If there were no route to the Internet Gateway, instances would be unable to reach any internet resources, not just DNS. Additionally, the Amazon-provided DNS server is internal to the VPC and doesn’t require an Internet Gateway route.
Option D is incorrect because network ACLs are stateless and require explicit rules for both inbound and outbound traffic, including ephemeral ports for response traffic. However, the default network ACL allows all inbound and outbound traffic, and blocking ephemeral ports would affect more than just DNS resolution—it would break most TCP connections and many UDP-based protocols.