We are pleased to announce ClassicLink DNS Support for Virtual Private Cloud (VPC). This feature enables support for DNS resolution of public hostnames to private IP addresses when queried over ClassicLink. A public DNS hostname of an instance in a VPC will resolve to private IP address when queried from a linked EC2-Classic instance. Similarly,a public DNS hostname of a linked EC2-Classic instance will resolve to private IP address when queried from an instance in the VPC. Additionally, you can now access private hosted zones associated with your VPC from a linked EC2-Classic instance. ClassicLink DNS support makes it easier for EC2-Classic instances to communicate with VPC resources using public DNS hostnames.
For more information see ‘Enable ClassicLink DNS Support’. You can learn more approximately ClassicLink, and here.
Source: amazon.com