Supporting global replicated services by a routing-metric-aware DNS

We propose domain name service (DNS) server extensions to support global replicated services. The DNS server collects routing metrics from routers for cached replicated servers. Upon receiving a DNS request from a host in its domain, the DNS automatically returns the IP address of a server available from an IP address pool that has the best routing metrics preferred by the host. Possible extensions to routers are proposed to support routing information collection. These router extensions work independently of the specific routing protocol used by the routers. The route metric collection mechanism is also independent of DNS extensions and may be used for other purposes. Our approach makes it much easier for content providers to support global replicated services flexibly and transparently. The network latency perceived by users is reduced substantially because of network proximity. Simulation results show that our approach is much better than DNS round robin. Moreover, the overhead introduced by our extension is negligible.