ANS-C01 Question 338
Select 3You are managing a hybrid network where your on-premises environment connects to AWS using a Direct Connect connection. You notice that certain routes from your on-premises environment are not being propagated to your Amazon VPC subnets. After verifying that the Direct Connect connection is active, what steps should you take to resolve the issue?
- A
Check if the routes are correctly advertised from the on-premises router to the Direct Connect Gateway.
- B
Verify if the route table associated with the VPC subnets includes the missing on-premises routes.
- C
Ensure that the Virtual Private Gateway (VGW) is properly attached to the VPC.
- D
Update the Direct Connect Gateway to use Border Gateway Protocol (BGP) instead of static routing.
- E
Confirm that there are no overlapping CIDR blocks between the VPC and on-premises network.
Show answer and explanation
Correct answers: A, B, E
Explanation
To maintain routing and connectivity in a hybrid AWS network, you must ensure that routes are properly advertised from the on-premises network to the Direct Connect Gateway, that the VPC subnet route tables include the required routes, and that there are no overlapping CIDR blocks causing conflicts. These steps will resolve the issue of missing routes and restore connectivity between on-premises and AWS resources.
- A. Correct.
Correct. Routes must be advertised from the on-premises router to the Direct Connect Gateway using BGP for them to propagate properly. If they are not advertised, they will not appear in the VPC routing tables.
- B. Correct.
Correct. The VPC subnet route table should explicitly include the routes for the on-premises network pointing to the Virtual Private Gateway (VGW). Without these entries, traffic will not flow correctly.
- C. Incorrect.
Incorrect. While the VGW must be attached to the VPC for connectivity, this is not the root cause of the issue described, as the Direct Connect connection is already active.
- D. Incorrect.
Incorrect. Direct Connect Gateway already uses BGP for dynamic routing, and static routing is not applicable here. Updating to BGP is unnecessary in this context.
- E. Correct.
Correct. Overlapping CIDR blocks between the VPC and on-premises network can cause routing conflicts, preventing routes from being propagated correctly.