An IT firm has created multiple VPCs as per project requirements which have customers` application servers deployed. The firm is planning to deploy a Direct Connect Link from its multiple offshore locations which need to access servers from VPC for monitoring & troubleshooting purposes. IT firm is looking for a highly available solution that can control traffic between VPC so that only specific subnets within those VPC can communicate with each other. As an AWS consultant, you have suggested implementing Transit Gateway & AWS Direct Connect Gateway.
Which of the below additional considerations should be followed while implementing the above suggestion sufficing client requirement?

Answer options:

A.Create separate subnets for each Transit gateway VPC attachments & enable BGP route propagations for AWS Direct Connect gateway attachments.
B.Create separate subnets for each Transit gateway VPC attachments & create an additional Transit Gateway for high availability.
C.Create a single subnet for each Transit gateway VPC attachments & enable BGP route propagations for AWS Direct Connect gateway attachments.
D.Create a single subnet for each Transit gateway VPC attachments & create an additional Transit Gateway for high availability.

Correct Answer – A
AWS Transit Gateway can be deployed to create full mesh or isolate VPC communication between VPC connecting to it as well as on-premises connectivity over AWS Direct Connect or VPN connections. Also, route propagation should be enabled for BGP routes from offshore locations to communicate with servers in all VPC.Option B is incorrect as an additional Transit gateway is not required as Transit gateway is by design highly available.
Options C & D are incorrect as configuring a single subnet for Transit gateway VPC attachments is not recommended.
For more information on AWS Transit Gateway, refer to the following URL
https://docs.aws.amazon.com/vpc/latest/tgw/tgw-best-design-practices.html