ANS-C01 Network Design Practice Question

Correct answer & explanation

Transit Gateway route tables propagate routes from VPC attachments. If both production VPCs are in the same route table, the routes for their CIDRs will be propagated. However, if there is a propagated route for the local VPC, it may override the static route or cause a conflict. The issue is likely that the static routes are being ignored because a more specific or conflicting propagated route exists, or the route table lacks a route for the remote production CIDR if the attachment is not associated correctly. Actually, the most common issue is that the production VPC attachments are in the same route table, but the static route for the remote production CIDR might be pointing to the VPC attachment itself, causing a loop. But the key point: Transit Gateway route tables do not allow overlapping CIDRs. Since both production VPCs have overlapping CIDRs (10.0.0.0/16 and 10.10.0.0/16 are different), that's not the issue. The issue is likely that the route table has a static route for the remote production CIDR, but the propagation from the local production VPC attachment might be creating a route that is not correct. The best answer is that the production VPC attachments need to be in separate route tables to avoid conflicting routes.