Abstract: In the distributed hash table (DHT),the identifiers of nodes are chosen at random,but this does not mean that the DHT is load-balanced. The simulation in Chord has shown that the load is imbalanced.The paper summarized the previous work on this problem to make clear that DHT is imbalanced essentially.We gave the precise scope of the upper bound of imbalance,and verified the results with simulations.

Key words: Peer-to-peer network, Distributed hash table (DHT) , Load balance, Probability distribution