AWS Certified SysOps Administrator – Associate — Question 354

A company has an AWS Site-to-Site VPN connection between on-premises resources and resources that are hosted in a VPC. A SysOps administrator launches an Amazon EC2 instance that has only a private IP address into a private subnet in the VPC. The EC2 instance runs Microsoft Windows Server.

A security group for the EC2 instance has rules that allow inbound traffic from the on-premises network over the VPN connection. The on-premises environment contains a third-party network firewall. Rules in the third-party network firewall allow Remote Desktop Protocol (RDP) traffic to flow between the on-premises users over the VPN connection.

The on-premises users are unable to connect to the EC2 instance and receive a timeout error.

What should the SysOps administrator do to troubleshoot this issue?

Answer options

• A. Create Amazon CloudWatch logs for the EC2 instance to check for blocked traffic.
• B. Create Amazon CloudWatch logs for the Site-to-Site VPN connection to check for blocked traffic.
• C. Create VPC flow logs for the EC2 instance's elastic network interface to check for rejected traffic.
• D. Instruct users to use EC2 Instance Connect as a connection method.

Correct answer: C

Explanation

Enabling VPC flow logs on the EC2 instance's network interface allows the administrator to capture and analyze IP traffic, showing whether RDP packets are arriving and if they are marked as REJECT (often due to Network ACLs). CloudWatch logs cannot monitor network packet rejections directly for EC2 instances or VPN connections without other configurations. EC2 Instance Connect is utilized for SSH access to Linux instances and does not support RDP connections to Windows Server.