Which of the following are possible causes of this issue?
(Choose two.)
A network ACL associated with the bastion’s subnet is blocking the network traffic.
The instance does not have a private IP address.
The route table associated with the bastion’s subnet does not have a route to the internet gateway.
The security group for the instance does not have an inbound rule on port 22.
The security group for the instance does not have an outbound rule on port 3389.
Explanations:
A network ACL associated with the bastion’s subnet could block inbound RDP traffic (port 3389). If the ACL denies this traffic, the user will be unable to establish a connection to the bastion server.
An Amazon EC2 instance always has a private IP address, regardless of whether it has a public IP address assigned. This means that the absence of a private IP address cannot be a cause for RDP connectivity issues.
If the route table associated with the bastion’s subnet does not have a route to the internet gateway, the instance will not be able to receive any inbound internet traffic, including RDP connections. This would prevent the user from connecting.
Port 22 is used for SSH (not RDP), which is irrelevant for RDP connections to a Windows instance. The correct port for RDP is 3389. Therefore, this option does not apply to the issue at hand.
An outbound rule on port 3389 is not necessary for incoming RDP connections. The outbound rules in security groups allow instances to respond to requests, but the user must have the appropriate inbound rule for port 3389 to establish the initial connection.
If I had to guess, I’d say the answer is:
A network ACL associated with the bastion’s subnet is blocking the network traffic.