Page "Distributed hash table" Paragraph 26

All DHT topologies share some variant of the most essential property: for any key, each node either has a node ID that owns or has a link to a node whose node ID is closer to, in terms of the keyspace distance defined above.

It is then easy to route a message to the owner of any key using the following greedy algorithm ( that is not necessarily globally optimal ): at each step, forward the message to the neighbor whose ID is closest to.

When there is no such neighbor, then we must have arrived at the closest node, which is the owner of as defined above.

This style of routing is sometimes called key-based routing.