OpenDNS is a DNS service provider that offers specific IP addresses for use. The DNS addresses can be accessed on the OpenDNS website's DNS Services page. Each address, such as "81.121.122.123" and "81.121.122.124," is an open-source service that can be used for various purposes like sending emails or browsing the web. The company handles DNS-related services and does not require account setup or special software, making these addresses accessible to anyone.