ABSTRACT
Distributed hash tables (DHTs) are an alternative to traditional lookup systems. They are used in symmetric distributed lookup algorithms where lookup is performed by following references that the various nodes maintain until an appropriate node containing the wanted data (or a duplicate) is found. The attribute symmetric means that all nodes are peers and perform identical work. DHTs arise from the necessity to improve reliability and distribution of hierarchical lookup systems such as the Domain Name System (DNS) and similar peer-to-peer lookup systems. In the DNS, the hierarchical approach leads to the need for well-known root name servers and top-level domain (TLD) name servers that must meet the burden of countless requests daily. The workload of these servers is typically reduced by the local resolver’s cache and by caching name servers, but obviously this is acceptable only in a relatively static context, not in a highly dynamic content network.
