An engineering firm is managing operations on Amazon EC2 instance using AWS Systems Manager. SSM agents on the EC2 instance are communicating with AWS System Manager over the interface VPC endpoint. Operations teams accessing AWS EC2 instance using Session Manager are unable to connect to this AWS EC2 instance. You have been assigned to troubleshoot this connectivity error.
Which additional interface endpoints need to be created to resolve this issue?

Answer options:

A.com.amazonaws.region.ec2messages interface VPC endpoint needs to be created in the us-east-1 region.
B.com.amazonaws.region.ec2 interface VPC endpoint needs to be created in the us-east-1 region.
C.com.amazonaws.region.ssmmessages interface VPC endpoint needs to be created in the us-east-1 region.
D.com.amazonaws.region.kms interface VPC endpoint needs to be created in the us-east-1 region.

Correct Answer: C
For secure communication between managed instance and Session Manager, additional interface VPC endpoint “com.amazonaws.region.ssmmessages” must be created. This interface VPC endpoint is different from the endpoint used for AWS Systems Manager.
Options A & B are incorrect as these interface VPC endpoints are used for connectivity to AWS Systems Manager & not for AWS Session manager.
Option D is incorrect as this interface VPC endpoint needs to be created only when AWS KMS is used with AWS Session Manager.
For more information on interface VPC endpoints for AWS Session Manager, refer to the following URL
https://docs.aws.amazon.com/systems-manager/latest/userguide/setup-create-vpc.html