nowadays we are announcing support for Virtual Private Cloud (VPC) ClassicLink in the Sao Paulo region. ClassicLink allows Amazon Elastic Compute Cloud (EC2) instances in the EC2-Classic platform to communicate with instances in a VPC using private IP addresses,instead of public addresses through the Internet. We are also announcing support for ClassicLink DNS support. This feature enables support for DNS resolution of public hostnames to private IP addresses when queried over ClassicLink, making it easier for EC2-Classic instances to communicate with VPC resources using public DNS hostnames.
Source: amazon.com