AWS Certified Advanced Networking – Specialty (ANS-C01) — Question 110

A network engineer is designing hybrid connectivity with AWS Direct Connect and AWS Transit Gateway. A transit gateway is attached to a Direct Connect gateway and 19 VPCs across different AWS accounts. Two new VPCs are being attached to the transit gateway. The IP address administrator has assigned 10.0.32.0/21 to the first VPC and 10.0.40.0/21 to the second VPC. The prefix list has one CIDR block remaining before the prefix list reaches the quota for the maximum number of entries.

What should the network engineer do to advertise the routes from AWS to on premises to meet these requirements?

Answer options

• A. Add 10.0.32.0/21 and 10.0.40.0/21 to both AWS managed prefix lists.
• B. Add 10.0.32.0/21 and 10.0.40.0/21 to the allowed prefix list.
• C. Add 10.0.32.0/20 to both AWS managed prefix lists.
• D. Add 10.0.32.0/20 to the allowed prefix list.

Correct answer: D

Explanation

The correct answer is D because adding the larger CIDR block of 10.0.32.0/20 to the allowed prefix list efficiently encompasses both 10.0.32.0/21 and 10.0.40.0/21 while staying within the quota limits. Options A and C do not address the quota issue correctly, and option B does not optimally consolidate the routes into one entry.