A network engineer created the following to connect two production VPCs in different Regions (Prod A in eu-west-1 with 10.0.0.0/16 and Prod B in eu-central-1 with 10.1.0.0/16): 1) one transit gateway in each Region, 2) shared and accepted the transit gateways with the production accounts, 3) created a peering attachment between the transit gateways, 4) attached each VPC to its Region's transit gateway, 5) created transit gateway route tables and associated attachments, 6) added static routes in each transit gateway route table to send traffic to the remote VPC, and 7) enabled route propagation on the VPC route tables. Connections from Prod A to Prod B failed. What should the engineer do to achieve the required connectivity?

The correct answer is to create a new route destined to 10.0.0.0/8 in both production VPC route tables with the Region transit gateway as the target. The existing setup correctly configures the Transit Gateway (TGW) peering and TGW route tables. However, the VPC route tables themselves need to be updated to direct traffic for the remote VPC's CIDR block (10.1.0.0/16 for Prod B, and 10.0.0.0/16 for Prod A) to their respective local TGW attachment. The 10.0.0.0/8 CIDR block is a common practice to encompass both VPCs' CIDRs (10.0.0.0/16 and 10.1.0.0/16) and direct all traffic for this range to the TGW. Modifying the IP address of the peering attachment is not relevant as peering attachments don't have IP addresses. Deleting static routes and enabling propagation in TGW route tables is incorrect because static routes are necessary for TGW peering, and propagation is typically from VPCs to TGW, not between TGWs for peered connections. Modifying TGW route tables to propagate routes dynamically between VPCs is not how TGW peering works; explicit routes are needed for inter-region TGW communication.