While not exactly the same, the Dynamo paper outlines that a single host is composed of many virtual nodes. It is very likely that a physical DynamoDB host will have dozens of nodes. This is done so that the cluster can scale up or down independent of the number of hosts while avoiding a gross imbalance. (12 nodes on 11 hosts means one host has 100% more traffic. 34 nodes on 11 hosts means one host has 33% more traffic.)