Your company needs to create its own VPN-based EC2 Instances. These Instances will allow 2 VPCs in different regions to talk to each other. You’ve created one VPN instance in one subnet in one VPC and another Instance in another subnet in another VPC. You are establishing the communication via the Internet gateway. What should extra consideration be in place in such a configuration?

Answer options:

A.Placing a NAT instance in front of both of the VPN connections
B.Placing a Virtual private gateway as the termination endpoint
C.Using a private hosted zone in Route 53
D.Having multiple VPN Instances for high availability

Answer - D
You have to consider the high availability of the Instances. In AWS Managed VPN, there are 2 tunnels created. So automatically there is high availability in place. But here, if either Instance goes down, the connection is broken.
Options A and C are incorrect since these are not key requirements.
Option B is incorrect since the individual EC2 Instances are the termination points.
For more information on such an example, please visit the below link
https://aws.amazon.com/articles/connecting-multiple-vpcs-with-ec2-instances-ipsec/