In order to provide 100% connectivity between all peers in all networks, DN includes support for relaying traffic between two peers through a third peer, called a relay. As long as there is connectivity between all peers and the relay, we can achieve 100% connectivity for all peers through this relay.
A relay is a special kind of host in the DN network that forwards traffic for two other hosts which cannot communicate directly with each other. Traffic flowing through the relay is end-to-end encrypted and authenticated, so the relay itself is not able to inspect or change this traffic, it only knows where it needs to be sent. To ensure 100% connectivity to the relay, the relay should be deployed like a lighthouse, with a public internet IP and with appropriate firewall rules in place.