In order to create RDS, I need to create a VPC and two subnets attached to it.
If I choose 10.0.0.0/16 as IPv4 CIDR for VPC, can you please suggest IPv4 CIDR blocks for the two subnets that I have to create?
You should split that up in to subnets with
/24, like this:
/24 in the
10.0.255.0 range is valid. I suggest reading the VPC and Subnet Basics in the AWS docs also.