AWS Certified Solutions Architect – Professional — Question 969
A company has VPC flow logs enabled for its NAT gateway. The company is seeing Action = ACCEPT for inbound traffic that comes from public IP address
198.51.100.2 destined for a private Amazon EC2 instance.
A solutions architect must determine whether the traffic represents unsolicited inbound connections from the internet. The first two octets of the VPC CIDR block are 203.0.
Which set of steps should the solutions architect take to meet these requirements?
Answer options
- A. Open the AWS CloudTrail console. Select the log group that contains the NAT gateway's elastic network interface and the private instance's elastic network interface. Run a query to filter with the destination address set as "like 203.0" and the source address set as "like 198.51.100.2". Run the stats command to filter the sum of bytes transferred by the source address and the destination address.
- B. Open the Amazon CloudWatch console. Select the log group that contains the NAT gateway's elastic network interface and the private instance's elastic network interface. Run a query to filter with the destination address set as "like 203.0" and the source address set as "like 198.51.100.2". Run the stats command to filter the sum of bytes transferred by the source address and the destination address.
- C. Open the AWS CloudTrail console. Select the log group that contains the NAT gateway's elastic network interface and the private instance's elastic network interface. Run a query to filter with the destination address set as "like 198.51.100.2" and the source address set as "like 203.0". Run the stats command to filter the sum of bytes transferred by the source address and the destination address.
- D. Open the Amazon CloudWatch console. Select the log group that contains the NAT gateway's elastic network interface and the private instance's elastic network interface. Run a query to filter with the destination address set as "like 198.51.100.2" and the source address set as "like 203.0". Run the stats command to filter the sum of bytes transferred by the source address and the destination address.
Correct answer: B
Explanation
VPC flow logs are published to Amazon CloudWatch Logs (or Amazon S3), not AWS CloudTrail, making CloudWatch the correct tool for analyzing these logs. To investigate unsolicited inbound traffic originating from the internet (198.51.100.2) and reaching the internal VPC network (first two octets 203.0), the source address must be filtered as 198.51.100.2 and the destination address as 203.0.