Amazon AWS Certified Advanced Networking — Specialty ANS-C01 Exam Dumps and Practice Test Questions Set15 Q211-225
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Question 211:
A company is implementing a disaster recovery strategy that requires replicating data from their primary VPC in us-east-1 to a secondary VPC in us-west-2. The data transfer must be encrypted in transit and should not traverse the public internet. The solution needs to support high throughput for large-scale data replication. What is the most appropriate networking solution?
A) Configure VPC peering between the two VPCs and enable encryption at the application layer
B) Use AWS Transit Gateway with inter-region peering and implement IPsec VPN for encryption
C) Establish VPC peering with encryption enabled and use private IP addresses for data transfer
D) Deploy AWS DataSync with VPC endpoints in both regions for private connectivity
Answer: B
Explanation:
AWS Transit Gateway with inter-region peering combined with IPsec VPN provides encrypted data transfer between regions without traversing the public internet while supporting high throughput requirements. Transit Gateway creates a hub-and-spoke network topology that simplifies connectivity between multiple VPCs and enables inter-region communication through Transit Gateway peering connections. When combined with VPN attachments, this architecture ensures that all data transferred between regions is encrypted at the network layer using IPsec protocols.
The implementation involves creating a Transit Gateway in each region, attaching the respective VPCs to their regional Transit Gateways, establishing VPN connections to each Transit Gateway, and then creating inter-region peering between the Transit Gateways. The VPN attachments provide automatic IPsec encryption for all traffic flowing through them, ensuring data is protected during transit. This approach supports high throughput because Transit Gateway can handle substantial bandwidth, and modern VPN implementations can achieve multi-gigabit per second performance when properly configured with appropriate encryption algorithms and instance types.
Option A is incorrect because while VPC peering can connect VPCs across regions and application-layer encryption can protect data, this approach requires the application to implement encryption rather than providing network-layer encryption. Additionally, VPC peering itself doesn’t provide built-in encryption, and inter-region VPC peering traffic, although it stays on AWS’s network, isn’t encrypted at the network layer unless the application implements it.
Option C is incorrect because VPC peering does not have a built-in encryption feature that can be enabled. VPC peering provides connectivity between VPCs but doesn’t offer network-layer encryption options. While peering connections use private IP addresses and traffic remains on AWS’s internal network, the data itself isn’t encrypted unless the application implements encryption.
Option D is incorrect because while AWS DataSync with VPC endpoints does provide private connectivity for data transfer and is excellent for file-based replication, it’s designed for specific data transfer scenarios rather than general network connectivity for disaster recovery. DataSync is typically used for migrating or synchronizing file systems, not for real-time application-level data replication between VPCs.
Question 212:
A financial institution needs to implement network monitoring that captures detailed information about all rejected connection attempts to their EC2 instances for security analysis. The monitoring solution should include source IP addresses, destination ports, and timestamps of rejected traffic. What AWS feature should be configured?
A) Enable VPC Flow Logs with a filter to capture only rejected traffic
B) Configure AWS CloudTrail to log all network connection attempts
C) Deploy AWS Network Firewall with custom rule logging
D) Enable Amazon GuardDuty for network anomaly detection
Answer: A
Explanation:
Enabling VPC Flow Logs with a filter configured to capture only rejected traffic is the most appropriate solution for monitoring and analyzing rejected connection attempts. VPC Flow Logs capture information about IP traffic going to and from network interfaces in your VPC, including comprehensive details about each connection attempt whether accepted or rejected. Flow Logs can be configured with filters to capture all traffic, only accepted traffic, or only rejected traffic, allowing you to focus on security-relevant events without collecting unnecessary data about normal operations.
When configured to capture rejected traffic, VPC Flow Logs record detailed information about each denied connection attempt including the source IP address, source port, destination IP address, destination port, protocol, packet count, byte count, timestamp, and the action taken. This information is invaluable for security analysis because it reveals potential attack patterns, identifies sources of malicious traffic, and helps validate that security group and network ACL rules are functioning as intended. The rejected traffic typically indicates that security controls blocked unauthorized access attempts, making this data critical for threat intelligence and compliance reporting.
Option B is incorrect because AWS CloudTrail logs API calls made to AWS services, not network connection attempts to EC2 instances. CloudTrail would record actions like creating or modifying security groups, but it doesn’t capture actual network packets or connection attempts at the IP level. CloudTrail is essential for auditing control plane activities but doesn’t provide the network traffic visibility required for this use case.
Option C is incorrect because while AWS Network Firewall can provide advanced traffic filtering and logging capabilities, it requires deploying and managing firewall infrastructure, which adds complexity and cost compared to VPC Flow Logs. Network Firewall is appropriate when you need deep packet inspection or sophisticated filtering rules beyond what security groups and network ACLs provide, but for simply logging rejected traffic, Flow Logs are more straightforward and cost-effective.
Option D is incorrect because Amazon GuardDuty is a threat detection service that analyzes VPC Flow Logs along with other data sources to identify potentially malicious activity, but it doesn’t directly provide the raw logs of rejected connection attempts. GuardDuty produces findings about suspicious behavior but doesn’t give you the detailed, comprehensive log data needed for custom security analysis and compliance reporting of all rejected traffic.
Question 213:
A company operates a multi-tier application with web servers in one VPC and database servers in another VPC in the same region. The application requires low-latency, high-bandwidth connectivity between the tiers. Security policies mandate that traffic between VPCs must be encrypted. What is the most efficient solution?
A) Establish VPC peering and configure application-level TLS encryption
B) Create a Transit Gateway with VPN attachments for both VPCs
C) Use AWS PrivateLink to connect the application to database services
D) Deploy AWS Direct Connect between the two VPCs
Answer: A
Explanation:
Establishing VPC peering combined with application-level TLS encryption provides the most efficient solution for low-latency, high-bandwidth connectivity between VPCs in the same region while meeting encryption requirements. VPC peering creates a direct networking connection between two VPCs using AWS’s internal network infrastructure, providing high throughput and minimal latency since traffic stays within AWS’s regional backbone. Unlike solutions that introduce additional network hops or processing overhead, VPC peering offers near-native performance characteristics ideal for latency-sensitive applications.
Application-level TLS encryption ensures that data transmitted between the web servers and database servers is protected during transit. Most modern databases support TLS connections natively, allowing applications to establish encrypted connections to databases with minimal configuration. By implementing encryption at the application layer, you maintain the performance benefits of VPC peering while satisfying security requirements. TLS encryption is processed by the application and database software rather than by intermediate network devices, allowing the underlying network path to remain optimized for performance.
Option B is incorrect because while Transit Gateway with VPN attachments provides encryption, it introduces unnecessary complexity and performance overhead for this use case. VPN encryption processing adds latency and reduces throughput compared to direct VPC peering with application-level encryption. Transit Gateway is valuable when connecting many VPCs or when you need centralized routing management, but for connecting just two VPCs in the same region with encryption requirements, it’s over-engineered and negatively impacts performance.
Option C is incorrect because AWS PrivateLink is designed for exposing services from one VPC to others, typically for service provider to consumer relationships. It requires the database tier to be exposed through a Network Load Balancer as a VPC endpoint service, adding complexity and additional network hops. PrivateLink is excellent for multi-tenant architectures where service isolation is paramount, but for connecting two tiers of the same application owned by the same organization, VPC peering is simpler and more efficient.
Option D is incorrect because AWS Direct Connect is designed for connecting on-premises data centers to AWS, not for connecting two VPCs within AWS. You cannot establish Direct Connect connections between VPCs—Direct Connect provides hybrid cloud connectivity. Even if you could theoretically route between VPCs through on-premises networks via Direct Connect, it would introduce enormous latency and complexity, making it completely inappropriate for this use case.
Question 214:
A company’s application uses Amazon ECS containers that need to pull Docker images from Amazon ECR and access configuration data stored in S3. The containers run in private subnets without internet access. What networking configuration enables the containers to access ECR and S3 without exposing them to the internet?
A) Deploy NAT Gateways in public subnets and route traffic through them
B) Configure VPC endpoints for ECR and S3 in the private subnets
C) Assign public IP addresses to containers temporarily during startup
D) Establish a Direct Connect connection to access AWS services privately
Answer: B
Explanation:
Configuring VPC endpoints for Amazon ECR and S3 in the private subnets enables containers to access these AWS services without requiring internet connectivity or NAT Gateways. VPC endpoints create private connections between your VPC and supported AWS services, allowing traffic to remain entirely within the AWS network. For this use case, you need both interface endpoints for ECR and a gateway endpoint for S3 to enable complete container functionality without internet exposure.
Amazon ECS containers pulling images from ECR actually require three VPC endpoints to function properly in fully private subnets. You need an interface endpoint for the ECR API, which containers use to authenticate and receive image manifests. You need an interface endpoint for ECR Docker registry, which provides the Docker registry API for image layers. Finally, you need a gateway endpoint for S3 because ECR stores the actual Docker image layers in S3 buckets. When all three endpoints are configured, containers can successfully pull images through completely private connectivity.
Interface endpoints create elastic network interfaces with private IP addresses in your specified subnets. These ENIs serve as entry points for traffic destined to the associated AWS services. When containers make requests to ECR, DNS resolution returns the private IP addresses of the interface endpoints rather than public ECR endpoints, and traffic flows through these endpoints over AWS’s private network. Gateway endpoints for S3 work differently—they’re specified as targets in route tables, directing S3-bound traffic through the gateway endpoint rather than to an Internet Gateway. Both endpoint types ensure traffic never leaves AWS’s network infrastructure.
Option A is incorrect because deploying NAT Gateways, while functional, requires that traffic destined for ECR and S3 traverse the NAT Gateway and reach AWS services through their public endpoints. This approach is less secure because traffic uses internet-routable IP addresses, incurs NAT Gateway processing and data transfer charges, and introduces an additional component that must be managed and could become a point of failure. VPC endpoints provide a more direct, cost-effective, and secure solution.
Option C is incorrect because temporarily assigning public IP addresses to containers defeats the security purpose of keeping them in private subnets. Even temporary internet exposure creates security risks and violates the principle of least privilege. Additionally, this approach would require complex orchestration to assign and remove public IPs during container lifecycle events, introducing operational complexity and potential for errors.
Option D is incorrect because AWS Direct Connect is used for connecting on-premises networks to AWS, not for enabling resources within AWS to access AWS services. ECS containers running in AWS VPCs don’t need Direct Connect to access other AWS services—VPC endpoints provide the necessary private connectivity within the AWS environment.
Question 215:
A network engineer is troubleshooting DNS resolution issues in a VPC where EC2 instances cannot resolve public domain names, but can communicate with other resources in the VPC using IP addresses. The VPC has both DNS resolution and DNS hostnames enabled. What is the most likely cause?
A) The instances are using a custom DHCP options set with incorrect DNS servers
B) Security groups are blocking DNS traffic on port 53
C) The route table is missing a route to the Internet Gateway
D) Network ACLs are blocking DNS responses on ephemeral ports
Answer: A
Explanation:
The instances using a custom DHCP options set with incorrect DNS servers is the most likely cause of DNS resolution failures when other VPC functionality works normally. DHCP options sets control what DNS servers EC2 instances use for name resolution. When you create a VPC, AWS automatically creates a default DHCP options set that specifies the Amazon-provided DNS server, which is located at the VPC base network address plus two. For example, in a VPC with CIDR 10.0.0.0/16, the Amazon DNS server is at 10.0.0.2.
If someone has created and associated a custom DHCP options set with the VPC, and that options set specifies DNS servers that are unreachable, misconfigured, or cannot resolve public DNS names, instances will experience DNS resolution failures. This is particularly common in hybrid cloud environments where administrators create custom DHCP options sets to point instances to on-premises DNS servers for internal name resolution. If those on-premises DNS servers cannot be reached from the VPC, or if they’re not configured to forward public DNS queries to internet DNS servers, public name resolution fails while IP-based communication continues to work.
Option B is incorrect because security groups are stateful and operate at the instance level. When an instance initiates a DNS query outbound, the response is automatically allowed back regardless of security group rules. Additionally, security groups don’t typically block outbound DNS traffic by default—most security groups allow all outbound traffic. While it’s theoretically possible to configure security groups to block DNS, this is extremely rare and would be an unusual configuration mistake.
Option C is incorrect because while a missing route to an Internet Gateway would prevent instances from accessing internet resources, it wouldn’t specifically affect only DNS resolution. If there were no route to the Internet Gateway, instances wouldn’t be able to reach any internet services, not just DNS. More importantly, the Amazon-provided DNS server is internal to the VPC and doesn’t require an Internet Gateway route to be accessible—it’s reached through the VPC’s internal routing.
Option D is incorrect because while network ACLs are stateless and do require explicit rules for return traffic including ephemeral ports, the default network ACL allows all inbound and outbound traffic. Unless someone has created custom network ACLs with restrictive rules, this wouldn’t be the issue. Additionally, if network ACLs were blocking DNS responses, this would affect DNS for all protocols, but the question indicates that IP-based communication works, suggesting that basic network connectivity including return traffic paths is functioning.
Question 216:
A company wants to implement a centralized network architecture where all internet-bound traffic from multiple VPCs is inspected by security appliances before reaching the internet. The solution should support automatic failover of security appliances and distribute traffic across multiple appliances for high availability. What architecture should be implemented?
A) Deploy security appliances in each VPC with local Internet Gateways
B) Use Transit Gateway with a centralized egress VPC containing security appliances behind a Gateway Load Balancer
C) Implement VPC peering to route all traffic through a security VPC with a single appliance
D) Configure AWS Network Firewall in each VPC for distributed inspection
Answer: B
Explanation:
Using AWS Transit Gateway with a centralized egress VPC containing security appliances deployed behind a Gateway Load Balancer provides a scalable, highly available solution for centralized traffic inspection. This architecture implements a hub-and-spoke model where all spoke VPCs route their internet-bound traffic through Transit Gateway to a central egress VPC. In the egress VPC, Gateway Load Balancer distributes traffic across multiple security appliances, providing both high availability through automatic failover and horizontal scalability through load distribution.
Gateway Load Balancer is specifically designed for inserting third-party virtual appliances like firewalls, intrusion detection systems, and deep packet inspection tools into the traffic path. It operates at Layer 3, preserving the source and destination IP addresses of the original packets, which is critical for security appliances that need to see actual client IP addresses for logging and policy enforcement. GWLB performs health checks on the security appliances and automatically routes traffic away from failed appliances to healthy ones, providing seamless failover without manual intervention. As traffic increases, you can scale by adding more security appliance instances behind the GWLB.
Option A is incorrect because deploying security appliances in each VPC with local Internet Gateways creates a distributed rather than centralized architecture. This approach requires deploying, managing, and updating security appliances in every VPC, multiplying operational complexity and costs. It doesn’t provide centralized policy management or consistent security controls across VPCs, and it’s difficult to ensure all VPCs maintain the same security posture as new VPCs are added.
Option C is incorrect because VPC peering doesn’t support transitive routing, making it impossible to efficiently route traffic from multiple VPCs through a central security VPC to reach the internet. You cannot route internet traffic through a peered VPC. Additionally, using a single security appliance creates a single point of failure that doesn’t meet the high availability requirement. While you could use VPC peering between each spoke and the security VPC, this doesn’t solve the transitive routing problem for internet egress.
Option D is incorrect because while AWS Network Firewall provides excellent security capabilities and can be deployed in each VPC, it represents a distributed inspection model rather than centralized inspection. Deploying Network Firewall in each VPC means managing firewall policies across multiple deployments, potentially leading to inconsistent security postures. It also multiplies costs and doesn’t provide the centralized visibility and control that the centralized architecture offers. Network Firewall is a valid solution but doesn’t meet the centralized requirement.
Question 217:
A company is migrating applications to AWS and needs to maintain their existing IP addressing scheme for compliance with hardcoded application configurations. Their on-premises network uses 172.16.0.0/12 address space. They plan to connect AWS to on-premises via Direct Connect. What should they consider when planning VPC CIDR blocks?
A) Use the same 172.16.0.0/12 range in AWS as used on-premises for consistency
B) Allocate non-overlapping subnets from the 172.16.0.0/12 range for AWS VPCs, reserving other subnets for on-premises
C) Use a completely different private IP range like 10.0.0.0/8 in AWS to avoid conflicts
D) Implement NAT to translate between on-premises and AWS address spaces
Answer: B
Explanation:
Allocating non-overlapping subnets from the 172.16.0.0/12 address range for AWS VPCs while reserving other subnets for on-premises use provides the best solution for maintaining address space consistency while ensuring proper routing functionality. This approach, called IP address space partitioning, allows the company to use addresses from their existing range in AWS, which satisfies compliance requirements and minimizes application reconfiguration, while avoiding the routing problems that would occur with completely overlapping address spaces.
The key to successful implementation is careful planning and documentation of IP address allocation. Before creating VPCs, the company should audit their current on-premises IP usage to identify which specific subnets within the 172.16.0.0/12 range are actively in use and which are available. For example, if on-premises currently uses 172.16.0.0/16 through 172.20.0.0/16, they could allocate 172.21.0.0/16 through 172.31.0.0/16 for AWS VPCs. This ensures that no subnet is used in both locations, which is essential for routing to function correctly.
Option A is incorrect because using the exact same CIDR range in both on-premises and AWS creates completely overlapping IP address spaces, which makes routing impossible. When the same IP addresses exist in multiple locations, routers cannot determine the correct destination for traffic, causing connectivity failures. This fundamental networking principle applies regardless of the specific technologies used for connectivity.
Option C is incorrect because while using a completely non-overlapping private IP range would work from a routing perspective, it defeats the purpose of maintaining the existing addressing scheme for compliance and application compatibility. If applications have hardcoded IP addresses or dependencies on the 172.16.0.0/12 range, moving to 10.0.0.0/8 would require extensive application reconfiguration, contradicting the stated requirement to maintain the existing scheme.
Option D is incorrect because implementing NAT to translate between address spaces adds significant complexity, introduces performance overhead, and can break applications that require end-to-end IP address visibility. NAT also complicates troubleshooting and logging since actual source IP addresses are hidden. Given that the company has a large private address range available, properly partitioning it is a much simpler and more effective solution than introducing translation.
Question 218:
A streaming media company operates a global application that requires users to download large video files. The company wants to reduce latency for users worldwide while minimizing data transfer costs from their origin servers in us-east-1. What AWS service configuration provides the most cost-effective solution?
A) Deploy Application Load Balancers in multiple regions with Route 53 latency-based routing
B) Configure Amazon CloudFront with origin in us-east-1 and enable compression for content delivery
C) Use Amazon S3 Transfer Acceleration for faster downloads globally
D) Deploy EC2 instances in multiple regions with Global Accelerator
Answer: B
Explanation:
Configuring Amazon CloudFront with an origin in us-east-1 and enabling compression provides the most cost-effective solution for global content delivery with reduced latency and minimized data transfer costs. CloudFront is AWS’s Content Delivery Network that caches content at edge locations distributed globally, bringing content physically closer to users and dramatically reducing the need to retrieve files from the origin server for every request. For video files that are accessed repeatedly by users worldwide, CloudFront’s caching mechanism results in substantial cost savings on data transfer from the origin.
CloudFront’s cost structure makes it particularly economical for this use case. When a user requests a video file, CloudFront serves it from the nearest edge location if it’s already cached. Only the first request for a file needs to be retrieved from the origin server in us-east-1, and subsequent requests from users in that geographic region are served directly from the cached copy at the edge location. Data transfer from the origin to CloudFront edge locations is free, meaning you only pay for data transfer from CloudFront edges to users, which is priced lower than standard data transfer from EC2 or S3 in most regions. The more cache hits CloudFront achieves, the greater the cost savings.
Option A is incorrect because deploying Application Load Balancers in multiple regions requires duplicating origin infrastructure in every region, significantly increasing costs for compute, storage, and cross-region data synchronization. While this provides low latency, it’s not cost-effective compared to CloudFront’s caching model. Additionally, data transfer from ALBs directly to users is more expensive than data transfer from CloudFront edge locations.
Option C is incorrect because S3 Transfer Acceleration is designed to speed up uploads to S3 and can also accelerate downloads, but it doesn’t provide caching like CloudFront. Every download would still retrieve the file from the origin S3 bucket, incurring full data transfer charges each time. Transfer Acceleration also adds per-request charges on top of standard S3 costs, making it more expensive than CloudFront for frequently accessed content.
Option D is incorrect because Global Accelerator improves application availability and performance by routing traffic through AWS’s global network to optimal endpoints, but it doesn’t cache content. All requests still reach the origin servers, incurring full data transfer costs for every download. Additionally, deploying EC2 instances in multiple regions multiplies infrastructure costs compared to using CloudFront’s managed edge network.
Question 219:
A financial services company requires that all network traffic logs be retained for seven years for regulatory compliance. The logs must be stored securely with encryption at rest and should be cost-optimized for long-term retention. VPC Flow Logs are currently published to CloudWatch Logs. What storage strategy should be implemented?
A) Keep Flow Logs in CloudWatch Logs and set a retention period of seven years
B) Configure Flow Logs to publish directly to S3 with S3 Glacier Deep Archive storage class and lifecycle policies
C) Export CloudWatch Logs to S3 daily, then transition to S3 Glacier Deep Archive after 30 days using lifecycle policies
D) Store logs in Amazon EBS volumes with snapshots taken monthly for backup
Answer: C
Explanation:
Exporting CloudWatch Logs to S3 on a daily basis and then transitioning them to S3 Glacier Deep Archive after 30 days using lifecycle policies provides the most cost-optimized solution for long-term log retention while maintaining accessibility for recent logs. This approach balances the need for operational access to recent logs with the cost savings of archival storage for older data that’s retained primarily for compliance purposes. CloudWatch Logs provides excellent real-time analysis and alerting capabilities for recent data, while S3 Glacier Deep Archive offers the lowest storage costs for long-term retention.
CloudWatch Logs charges are based on data ingested, data stored, and data retrieved. For seven years of retention, storage costs in CloudWatch Logs would be substantial because CloudWatch storage is priced for active, frequently accessed data. By exporting logs to S3 and eventually moving them to Glacier Deep Archive, you reduce storage costs by over 95% compared to keeping everything in CloudWatch Logs. The daily export ensures that operational teams maintain easy access to recent logs in CloudWatch for troubleshooting and analysis, while older logs transition to cost-effective archival storage.
Option A is incorrect because keeping Flow Logs in CloudWatch Logs for seven years would be extremely expensive. CloudWatch Logs storage is designed for operational data that’s actively queried and analyzed, not for long-term archival. The storage costs would far exceed the costs of exporting to S3 and using Glacier Deep Archive, potentially costing tens or hundreds of times more for the same data retention period.
Option B is incorrect because while publishing Flow Logs directly to S3 avoids CloudWatch Logs costs, it eliminates the real-time analysis and alerting capabilities that CloudWatch Logs provides for recent data. Organizations typically need to monitor recent logs for security events and troubleshooting. By using CloudWatch Logs for recent data and archiving to S3, you get both operational visibility and cost-effective long-term storage.
Option D is incorrect because storing logs on EBS volumes is completely inappropriate for log archival. EBS volumes are expensive compared to S3, require manual management including snapshot scheduling and retention policies, and don’t provide the durability guarantees of S3. EBS is designed for block storage attached to EC2 instances, not for log archival. This approach would be operationally complex, expensive, and risky compared to using S3’s purpose-built storage classes for archival data.
Question 220:
A company is deploying a high-performance computing cluster that requires extremely low latency and high bandwidth communication between compute nodes. The application uses MPI for inter-node communication and is sensitive to network jitter. What instance placement and networking configuration should be used?
A) Deploy instances in a spread placement group across multiple Availability Zones with Enhanced Networking
B) Use a cluster placement group in a single Availability Zone with instances supporting Elastic Fabric Adapter
C) Distribute instances across multiple Availability Zones using a partition placement group
D) Deploy instances in a single subnet with multiple Elastic Network Interfaces per instance
Answer: B
Explanation:
Using a cluster placement group in a single Availability Zone with instances supporting Elastic Fabric Adapter provides the optimal configuration for high-performance computing workloads requiring ultra-low latency and high bandwidth. Cluster placement groups pack instances in close physical proximity within a single Availability Zone, minimizing the distance network packets must travel and reducing latency to the microsecond range. EFA provides OS-bypass capabilities that allow MPI applications to communicate directly with network hardware without kernel involvement, dramatically reducing latency and jitter.
Elastic Fabric Adapter is specifically designed for HPC and machine learning workloads that use collective communication patterns like those found in MPI applications. EFA provides all the capabilities of Enhanced Networking plus an additional OS-bypass feature that enables applications to access the network interface directly, bypassing the operating system kernel. This direct hardware access eliminates context switching and kernel processing overhead, resulting in significantly lower and more consistent latency. For MPI workloads where nodes constantly communicate to synchronize computations, even small latency reductions multiply across thousands of messages to produce substantial performance improvements.
Cluster placement groups complement EFA by ensuring physical proximity of instances. When instances are placed close together, network latency is minimized because packets traverse shorter physical distances and fewer network hops. AWS attempts to provision instances in a cluster placement group in the same rack or nearby racks within the data center, providing single-digit microsecond latency between instances. This is critical for tightly-coupled parallel applications where computation on one node depends on results from other nodes. The combination of cluster placement for physical proximity and EFA for optimized network access creates the ideal environment for HPC workloads.
Option A is incorrect because spread placement groups are designed to distribute instances across distinct underlying hardware to reduce correlated failures, not to optimize for low latency. Spreading instances across multiple Availability Zones introduces significant additional latency because data must traverse between different data centers, typically adding several milliseconds of latency. While Enhanced Networking improves performance, it cannot overcome the latency introduced by physical distance between Availability Zones.
Option C is incorrect because partition placement groups are designed for distributed and replicated workloads like Hadoop and Cassandra that need to be spread across logical partitions to avoid correlated hardware failures. Partition groups don’t optimize for low latency between instances. Additionally, distributing across multiple Availability Zones introduces unacceptable latency for tightly-coupled HPC applications that require rapid inter-node communication.
Option D is incorrect because adding multiple Elastic Network Interfaces to instances doesn’t improve performance for inter-instance communication. Multiple ENIs are useful for separating management and data traffic or attaching instances to multiple subnets, but they don’t reduce latency or increase bandwidth for node-to-node communication. Without cluster placement and EFA, instances would experience higher latency regardless of ENI configuration.
Question 221:
A company needs to establish connectivity between their VPC and an on-premises data center. The connection must support bandwidth up to 10 Gbps and provide a consistent, reliable connection with predictable performance. The company wants to avoid variability associated with internet connections. What AWS service should be implemented?
A) AWS Site-to-Site VPN with multiple tunnels for aggregated bandwidth
B) AWS Direct Connect with a 10 Gbps dedicated connection
C) VPN connection over AWS Direct Connect for encrypted high-bandwidth connectivity
D) AWS PrivateLink for private connectivity to on-premises services
Answer: B
Explanation:
AWS Direct Connect with a 10 Gbps dedicated connection provides the most appropriate solution for establishing high-bandwidth, reliable connectivity with predictable performance between a VPC and on-premises data center. Direct Connect creates a dedicated network connection between your on-premises infrastructure and AWS, bypassing the public internet entirely. This dedicated connection eliminates the variability, congestion, and unpredictable performance characteristics associated with internet-based connectivity, providing consistent network performance ideal for enterprise workloads.
Direct Connect offers various port speeds including 1 Gbps, 10 Gbps, and 100 Gbps dedicated connections. For this requirement, a 10 Gbps dedicated connection directly meets the bandwidth requirement. The dedicated nature of the connection means that the full bandwidth is available exclusively for your traffic, without contention from other users or internet congestion. This predictability is crucial for applications with consistent high-bandwidth requirements such as database replication, backup and disaster recovery, large data transfers, or latency-sensitive applications.
Option A is incorrect because while Site-to-Site VPN can provide secure connectivity over the internet, VPN connections are limited to 1.25 Gbps per tunnel, and you cannot aggregate multiple VPN tunnels to achieve 10 Gbps bandwidth. Even with multiple VPN connections, each connection operates independently, and applications cannot utilize the combined bandwidth. Additionally, VPN performance varies based on internet conditions, contradicting the requirement for consistent, predictable performance.
Option C is incorrect because while running VPN over Direct Connect combines the dedicated bandwidth of Direct Connect with encryption, it’s addressing a different use case. The question doesn’t specify a requirement for encryption beyond what application-layer security might provide. Running VPN over Direct Connect adds encryption processing overhead that can reduce effective throughput and increase latency. If encryption is required, MACsec encryption on Direct Connect or application-layer encryption are more appropriate than VPN.
Option D is incorrect because AWS PrivateLink is designed for exposing services from one VPC to others or to on-premises networks, not for establishing general connectivity between a VPC and on-premises data center. PrivateLink is a service-to-service connectivity technology focused on specific application endpoints, not a replacement for Direct Connect or VPN for hybrid cloud network connectivity.
Question 222:
A network administrator needs to implement a solution that allows EC2 instances to automatically receive both IPv4 and IPv6 addresses. The VPC has been configured with both IPv4 and IPv6 CIDR blocks, and subnets have been assigned both address types. What additional configuration is required for instances to receive IPv6 addresses automatically?
A) Enable IPv6 globally on the VPC, which automatically assigns IPv6 to all instances
B) Configure subnet auto-assign IPv6 settings and launch instances with IPv6 enabled
C) Assign IPv6 addresses manually to each instance after launch
D) Create a DHCP options set that includes IPv6 DNS servers
Answer: B
Explanation:
Configuring subnet auto-assign IPv6 settings and launching instances with IPv6 enabled provides the correct approach for automatically assigning IPv6 addresses to instances. Even after associating IPv6 CIDR blocks with a VPC and subnets, instances don’t automatically receive IPv6 addresses unless the subnet is explicitly configured to auto-assign them. This is a two-step process: first, enable the auto-assign IPv6 address setting on the subnet, and second, ensure instances are launched with IPv6 support enabled either through the launch configuration or by accepting the default when the subnet has auto-assign enabled.
The subnet-level auto-assign IPv6 setting controls whether new instances launched in that subnet automatically receive an IPv6 address from the subnet’s IPv6 CIDR block. When this setting is enabled, new instances get both their IPv4 address and an IPv6 address at launch without requiring manual intervention. The IPv6 address is assigned from the subnet’s /64 IPv6 CIDR block, and the specific address is typically selected automatically by AWS, though you can specify a particular address if needed. This automatic assignment simplifies dual-stack deployments by ensuring consistency and reducing manual configuration errors.
Option A is incorrect because there is no global IPv6 enable setting for VPCs that automatically assigns IPv6 to all instances. IPv6 enablement requires configuration at multiple levels including associating IPv6 CIDR blocks with the VPC and subnets, configuring subnet auto-assign settings, updating route tables and security rules, and ensuring instances are launched with IPv6 enabled. Each of these steps must be performed explicitly—there’s no single switch that automatically configures everything.
Option C is incorrect because while you can manually assign IPv6 addresses to instances after launch by adding them to the network interface, this approach doesn’t scale well and defeats the purpose of having automatic address assignment capabilities. Manual assignment is error-prone, time-consuming for large deployments, and doesn’t provide the operational benefits of automated configuration. The auto-assign subnet setting exists specifically to avoid the need for manual address management.
Option D is incorrect because DHCP options sets in AWS VPCs control what DNS servers instances use, but they don’t directly affect IPv6 address assignment. IPv6 address assignment is handled through the subnet auto-assign setting and instance launch configuration, not through DHCP options. While you might configure DNS servers that support both IPv4 and IPv6 name resolution, this is separate from the IPv6 address assignment process itself.
Question 223:
A company operates a SaaS platform that serves hundreds of customer organizations. Each customer’s data must be completely isolated at the network level. The company wants to provide customers with private connectivity to the platform without exposing services to the public internet. What AWS architecture should be implemented?
A) Create separate VPCs for each customer and use VPC peering for connectivity
B) Deploy the SaaS platform with AWS PrivateLink, allowing customers to create VPC endpoints
C) Use separate security groups for each customer within a shared VPC
D) Implement AWS Transit Gateway with isolated route tables for each customer
Answer: B
Explanation:
Deploying the SaaS platform with AWS PrivateLink and allowing customers to create VPC endpoints provides the scalable, secure architecture needed for multi-tenant SaaS with network-level isolation. PrivateLink enables the service provider to expose their application as a VPC endpoint service, which customers can then access by creating interface VPC endpoints in their own VPCs. This architecture ensures that each customer’s traffic flows through a dedicated network path, providing network-level isolation while keeping all traffic within AWS’s private network without traversing the internet.
The PrivateLink architecture works by having the service provider deploy their SaaS application behind a Network Load Balancer and configure that NLB as a VPC endpoint service. The service can be made available to specific AWS accounts by whitelisting account IDs, or configured to allow discovery by any AWS account with approval required for each connection request. When a customer wants to connect, they create an interface VPC endpoint in their VPC that references the service provider’s endpoint service name. The service provider reviews and approves the connection request, after which the customer can access the service through the endpoint.
Option A is incorrect because creating separate VPCs for each customer with VPC peering doesn’t scale for hundreds of customers. Each customer VPC would require a peering connection to the service provider’s VPC, and VPC peering connections must be managed individually. With hundreds of customers, this creates significant operational overhead. Additionally, VPC peering creates tighter coupling between the service provider and customers than PrivateLink, potentially exposing more of the service provider’s internal network architecture.
Option C is incorrect because while security groups can control access to resources, they operate at the instance level within a VPC and don’t provide network-level isolation between customers. Using a shared VPC with only security groups for separation doesn’t meet the requirement for complete network-level isolation. All customers would share the same network space, and misconfigurations could potentially allow cross-customer traffic. This architecture is also less scalable as the number of security group rules would grow substantially with hundreds of customers.
Option D is incorrect because AWS Transit Gateway with isolated route tables is designed for connecting multiple VPCs and on-premises networks in hub-and-spoke architectures, not for providing service access to external customers. While Transit Gateway can provide isolation through separate route tables, requiring customers to connect their VPCs to the service provider’s Transit Gateway creates tight coupling and complex networking configurations. PrivateLink provides a more appropriate service-to-consumer model for SaaS architectures.
Question 224:
A financial application requires that database connections from application servers be logged with detailed information including connection timestamps, source IP addresses, and SQL statements executed. The application uses Amazon RDS PostgreSQL. What combination of features should be enabled to capture this information?
A) Enable VPC Flow Logs to capture database connection metadata
B) Enable RDS Enhanced Monitoring for detailed database metrics
C) Configure PostgreSQL parameter group to enable query logging and publish logs to CloudWatch Logs
D) Enable AWS CloudTrail to log all database API calls
Answer: C
Explanation:
Configuring the PostgreSQL parameter group to enable query logging and publishing those logs to CloudWatch Logs provides the detailed database activity logging required for security and compliance purposes. RDS PostgreSQL supports extensive logging capabilities through database parameters that control what information is logged, including connection attempts, disconnections, query statements, and execution durations. By enabling these logging parameters and configuring RDS to publish database logs to CloudWatch Logs, you create a comprehensive audit trail of database activity accessible for analysis, alerting, and long-term retention.
The specific PostgreSQL parameters that should be configured include log_connections to log all connection attempts, log_disconnections to log disconnections, log_statement to log SQL statements, and log_duration or log_min_duration_statement to log query execution times. These parameters are set in the DB parameter group associated with the RDS instance. The log_statement parameter can be set to ‘all’ to log every SQL statement, ‘ddl’ to log only data definition statements like CREATE and ALTER, ‘mod’ to log data modification statements like INSERT, UPDATE, and DELETE, or ‘none’ to disable statement logging. For comprehensive auditing, setting it to ‘all’ captures every query.
Once logging is enabled at the database level, configuring RDS to publish logs to CloudWatch Logs makes them accessible for centralized monitoring and analysis. In the RDS console, you can enable log exports for the postgresql log, which automatically streams database logs to CloudWatch Logs in near real-time. From CloudWatch Logs, you can create metric filters to detect specific patterns like failed login attempts or suspicious queries, set up alarms for security events, and export logs to S3 for long-term archival. The logs include timestamps, source IP addresses from the VPC, usernames, database names, and the full text of executed SQL statements, providing complete visibility into database activity.
Option A is incorrect because VPC Flow Logs capture network-level information about connections including source and destination IP addresses and ports, but they don’t capture application-layer details like SQL statements. Flow Logs can tell you that a connection was established between an application server and database, but they cannot reveal what queries were executed or what data was accessed. For database activity auditing, you need application-layer logging from the database itself.
Option B is incorrect because RDS Enhanced Monitoring provides detailed operating system metrics like CPU usage, memory utilization, disk I/O, and network statistics. While valuable for performance monitoring and troubleshooting, Enhanced Monitoring doesn’t log connection details or SQL query statements. It operates at the infrastructure layer, not the application layer, and doesn’t provide the audit trail of database activity required for security compliance.
Option D is incorrect because AWS CloudTrail logs API calls made to AWS services, including RDS management operations like creating databases, modifying configurations, or taking snapshots. CloudTrail does not log database queries or connections made to the RDS instance itself. CloudTrail operates at the AWS control plane level, recording who made what changes to AWS resources, but it doesn’t capture application-level activity within the database.
Question 225:
A company’s network security policy requires implementing defense in depth for a web application. The application runs on EC2 instances behind an Application Load Balancer. What combination of security controls provides the most comprehensive protection?
A) Security groups on ALB and instances, with AWS WAF attached to the ALB
B) Network ACLs only, configured to allow only HTTP and HTTPS traffic
C) Security groups only, with rules referencing other security groups
D) AWS Shield Advanced for DDoS protection without additional controls
Answer: A
Explanation:
Implementing security groups on both the Application Load Balancer and EC2 instances, combined with AWS WAF attached to the ALB, provides comprehensive defense in depth through multiple layers of security controls. This layered approach ensures that even if one security control is bypassed or misconfigured, other controls provide protection. Each layer operates at a different level of the network stack and provides different capabilities, creating overlapping defenses that significantly improve overall security posture.
Security groups operate at the instance and ALB level, controlling traffic based on protocols, ports, and source IP addresses or other security groups. The ALB’s security group should allow inbound HTTP and HTTPS traffic from the internet, while the instance security group should allow traffic only from the ALB’s security group on the application port. This creates a defense layer where even if someone discovers the instances’ IP addresses, they cannot directly connect because the instance security group only accepts traffic from the ALB. Security group rules using source security group references are particularly powerful because they automatically adapt as instances are added or removed, maintaining security without manual updates.
AWS WAF provides application-layer protection by inspecting HTTP and HTTPS requests and filtering traffic based on configurable rules. WAF can block common web exploits like SQL injection and cross-site scripting, implement rate limiting to prevent abuse, create IP-based allowlists or blocklists, and filter based on geographic location. WAF rules are evaluated before traffic reaches the ALB’s listeners, blocking malicious requests at the application layer before they consume backend resources. This is critical because security groups operate at the network layer and cannot detect malicious payloads hidden within legitimate HTTP traffic.
Option B is incorrect because relying solely on network ACLs provides only a single layer of defense at the subnet level. Network ACLs are stateless and operate based on IP addresses and ports, making them unable to detect application-layer attacks. Using only network ACLs doesn’t implement defense in depth and leaves the application vulnerable to many attack vectors that security groups and WAF can prevent. Additionally, network ACL management is more complex than security groups for dynamic environments.
Option C is incorrect because while security groups provide effective instance-level protection, using only security groups doesn’t implement complete defense in depth. Security groups cannot inspect HTTP request contents to detect SQL injection, XSS, or other application-layer attacks. Without WAF, the application remains vulnerable to web exploits that security groups cannot detect. Multiple layers of different types of controls are needed for true defense in depth.
Option D is incorrect because while AWS Shield Advanced provides excellent DDoS protection and is valuable for high-profile applications, DDoS protection alone doesn’t constitute comprehensive security. Shield Advanced protects against volumetric network attacks and application-layer DDoS but doesn’t provide the granular access control of security groups or the application-layer filtering of WAF. Comprehensive protection requires multiple types of controls addressing different attack vectors, not reliance on a single service regardless of its capabilities.