AWS Certified Advanced Networking – Specialty (ANS-C01) — Question 198

A company is replatforming a legacy data processing solution to AWS. The company deploys the solution on Amazon EC2 Instances in private subnets that are in one VPC.

The solution uses Amazon S3 for abject storage. Both the data that the solution processes and the data the solution produces are stored in Amazon S3. The solution uses Amazon DynamoDB to save its own state. The company collects flow logs for the VPC. The solution uses one NAT gateway to register its license through the internet. A software vendor provides a specific hostname so the solution can register its license.

The company notices that the AWS bill exceeds the projected budget for the solution. A network engineer uses AWS Cost Explorer to investigate the bill. The network engineer notices that the USE2-NatGateway-Bytes($) usage type is the root cause of the higher than expected bill.

What should the network engineer do to resolve the issue? (Choose two.)

Answer options

• A. Set up Amazon VPC Traffic Mirroring. Analyze the traffic to identify the traffic that the NAT gateway processes.
• B. Examine the VPC flow logs to identity the traffic that traverses the NAT gateway.
• C. Set up an AWS Cost and Usage Report in the AWS Billing and Cost Management console. Examine the report to find more details about the NAT gateway charges.
• D. Verify that the security groups attached to the EC2 instances allow outgoing traffic only to the IP addresses that the hostname resolves to, the VPC CIDR block, and the AWS IP address ranges for Amazon S3 and DynamoDB.
• E. Verify that the gateway VPC endpoints for Amazon S3 and DynamoDB are both set up and associated with the route tables of the private subnets.

Correct answer: B, E

Explanation

The correct actions are to examine the VPC flow logs (Option B) to understand the traffic going through the NAT gateway, and to ensure that the gateway VPC endpoints for Amazon S3 and DynamoDB (Option E) are in place, which can help reduce NAT gateway usage by allowing direct access. The other options either do not directly address the cost issue or involve unnecessary complexity without targeting the root cause of the high charges.