Recently I learned from a co-worker that you could add additional CIDR blocks to an existing VPC. After working with the AWS platform for over 10 years I must say that I had no idea this was possible. Sometimes we get so caught up on the day-to-day builds that exploring new tweaks gets pushed to the side until someone asks for a specific feature or change. The most interesting thing about this is AWS doesn’t seem to publish a whole lot about it. This one article/guide was found on AWS as of this blog post: AWS – Adding additional CIDR blocks to an existing VPC. AWS VPC Guide <– I downloaded the PDF guide for reference, so have a look on page 82 “Adding IPv4 CIDR Blocks to a VPC (p. 82)”.