domain name service
A domain name service (DNS) is a computer program (aka "process" or "daemon") which looks up and returns the IP address for each domain name it is given. Due to the design of the internet, the local program must talk to an "upstream server" in order to find out information about domain names that it doesn't already know; this upstream service is generally included as part of the service provided by an internet service provider.
Wikipedia refers to domain name service software as "Domain Name System software", which is technically correct but doesn't distinguish between the system overall and the particular component which represents the overall system as a service within a given network.
- distributed DNS is a form of DNS that is decentralized and does not ultimately rely on a central domain name registry