A user has created a VPC with CIDR 20.0.0.0/16. The user has created one subnet with CIDR 20.0.0.0/16 in this VPC. The user is trying to create another subnet with the same VPC for CIDR 20.0.0.0/24. What will happen in this scenario?

Answer options:

A.It will throw a CIDR overlap error.
B.It is not possible to create a subnet with the same CIDR as the VPC.C.The second subnet will be created.
D.The VPC will modify the first subnet to allow this IP range.

Answer - A
Since the CIDR of the new subnet overlaps with that of the first subnet, an overlap error will be displayed. See the snapshot below.
For more information on VPC subnets, please refer to the below link.
http://docs.aws.amazon.com/AmazonVPC/latest/UserGuide/VPC_Subnets.html