AWS Certified Solutions Architect – Professional — Question 1014
A company has created an account for individual Development teams, resulting in a total of 200 accounts. All accounts have a single virtual private cloud (VPC) in a single region with multiple microservices running in Docker containers that need to communicate with microservices in other accounts. The Security team requirements state that these microservices must not traverse the public internet, and only certain internal services should be allowed to call other individual services. If there is any denied network traffic for a service, the Security team must be notified of any denied requests, including the source IP.
How can connectivity be established between service while meeting the security requirements?
Answer options
- A. Create a VPC peering connection between the VPCs. Use security groups on the instances to allow traffic from the security group IDs that are permitted to call the microservice. Apply network ACLs and allow traffic from the local VPC and peered VPCs only. Within the task definition in Amazon ECS for each of the microservices, specify a log configuration by using the awslogs driver. Within Amazon CloudWatch Logs, create a metric filter and alarm off of the number of HTTP 403 responses. Create an alarm when the number of messages exceeds a threshold set by the Security team.
- B. Ensure that no CIDR ranges are overlapping, and attach a virtual private gateway (VGW) to each VPC. Provision an IPsec tunnel between each VGW and enable route propagation on the route table. Configure security groups on each service to allow the CIDR ranges of the VPCs in the other accounts. Enable VPC Flow Logs, and use an Amazon CloudWatch Logs subscription filter for rejected traffic. Create an IAM role and allow the Security team to call the AssumeRole action for each account.
- C. Deploy a transit VPC by using third-party marketplace VPN appliances running on Amazon EC2, dynamically routed VPN connections between the VPN appliance, and the virtual private gateways (VGWs) attached to each VPC within the region. Adjust network ACLs to allow traffic from the local VPC only. Apply security groups to the microservices to allow traffic from the VPN appliances only. Install the awslogs agent on each VPN appliance, and configure logs to forward to Amazon CloudWatch Logs in the security account for the Security team to access.
- D. Create a Network Load Balancer (NLB) for each microservice. Attach the NLB to a PrivateLink endpoint service and whitelist the accounts that will be consuming this service. Create an interface endpoint in the consumer VPC and associate a security group that allows only the security group IDs of the services authorized to call the producer service. On the producer services, create security groups for each microservice and allow only the CIDR range of the allowed services. Create VPC Flow Logs on each VPC to capture rejected traffic that will be delivered to an Amazon CloudWatch Logs group. Create a CloudWatch Logs subscription that streams the log data to a security account.
Correct answer: D
Explanation
AWS PrivateLink (Option D) is the ideal solution for connecting services across 200 accounts because VPC peering has a hard limit of 125 active connections per VPC, making a full mesh peering topology impossible. PrivateLink keeps all traffic within the AWS backbone network, allows fine-grained access control by whitelisting specific AWS accounts, and secures access using security groups on the interface endpoints. Finally, enabling VPC Flow Logs and streaming them to a central security account allows the Security team to capture and analyze blocked connection attempts (including the source IP) at the network layer.