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?
To determine whether the traffic is unsolicited inbound traffic from the internet, you need to identify if there was any initial outbound communication from the private Amazon EC2 instance that would have solicited the inbound traffic. This involves checking the logs for outbound traffic from the private EC2 instance to see if it initiated communication with the public IP address 198.51.100.2. Therefore, you need to query the logs with the destination address set as 198.51.100.2 and the source address set as 203.0, which corresponds to the private instance within the VPC CIDR block, to see if such communication exists. This makes option D the correct choice.
D The question already states that there was an Action=Accept from Internet inbound to Private IP. The goal is to determine if this was solicited or unsolicited traffic. If solicited, traffic would have been initiated from the Private IP address initially and then received the return traffic. If unsolicited, there would be no initial traffic outbound from Private IP address. So Answer D is what is needed to determine this.
Good explication
https://aws.amazon.com/premiumsupport/knowledge-center/vpc-analyze-inbound-traffic-nat-gateway/
Thank you for the link. This explains it perfectly. The answer is actually D because it is assumed that reason #1 is already complete as the questions states that incoming traffic has been confirmed. Now the question is focusing on reason #2 to see if it was solicited meaning that the private ec2 instance initiated the traffic.
Apologies you were correct I mixed up the letters. I down vote my mistake.
As a networking guy, D is the obvious answer. You are inspecting the CW log group for the outbound traffic.
Agree with sb333 we need to observe egress to determine if it was solicited https://aws.amazon.com/premiumsupport/knowledge-center/vpc-analyze-inbound-traffic-nat-gateway/ by Cloudxie says "select appropriate log"
B: Cloudxie added the link https://aws.amazon.com/premiumsupport/knowledge-center/vpc-analyze-inbound-traffic-nat-gateway/ D is the case when we want to know if Traffic to the public IP was initiated from a private instance filter (dstAddr like 'public IP' and srcAddr like 'xxx.xxx')
traffic to the public IP was initiated from a private instance filter (dstAddr like 'public IP' and srcAddr like 'xxx.xxx') | stats sum(bytes) as bytesTransferred by srcAddr, dstAddr | limit 10
D is correct. sb333 explained it very well.
Cloudtrail isn't used to view VPC flow logs, so that rules out A and C. Traffic is already allowed inbound, so need to see if there is suspicious traffic from the source/internal/private range = 203.0 Source = 203.x Dest = 198.51
D. - to determine that it 's unsolicited or not.
Answer is D
should be B Cloudxie posted this link here you can see https://aws.amazon.com/premiumsupport/knowledge-center/vpc-analyze-inbound-traffic-nat-gateway/ filter (dstAddr like 'xxx.xxx' and srcAddr like 'public IP') | stats sum(bytes) as bytesTransferred by srcAddr, dstAddr | limit 10 Query results show traffic on the NAT gateway private IP from the public IP, but not traffic on other private IPs in the VPC. These results confirm that the incoming traffic was unsolicited. However, if you do see traffic on the private instance's IP, then follow the steps under Reason
The question already states "Action=Accept from Internet inbound to Private IP" Option 'D' fulfils that condition.
Correct B.
Changed D. You need to 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", and run the stats command to filter the sum of bytes transferred by the source address and the destination address.
https://aws.amazon.com/premiumsupport/knowledge-center/vpc-analyze-inbound-traffic-nat-gateway/
Flow log data can be published to the following locations: Amazon CloudWatch Logs, Amazon S3, or Amazon Kinesis Data Firehose. - A is out.
same question in version 2 https://www.examtopics.com/discussions/amazon/view/95384-exam-aws-certified-solutions-architect-professional-sap-c02/ B is correct
B https://repost.aws/knowledge-center/vpc-analyze-inbound-traffic-nat-gateway from aws documentation: filter (dstAddr like 'xxx.xxx' and srcAddr like 'public IP') | stats sum(bytes) as bytesTransferred by srcAddr, dstAddr | limit 10 if the query results show traffic ONLY ON the NAT gateway private IP from the public IP, BUT NOT traffic on other private IPs in the VPC, these results confirm that the incoming traffic was unsolicited.