The Domain Name System (DNS) is a distributed Internet directory service. DNS is used mostly to translate between domain names and IP addresses, and to control Internet email delivery. Most Internet services rely on DNS to work, and if DNS fails, web sites cannot be located and email delivery stalls. The DNS directory service consists of DNS data, DNS servers, and Internet protocols for fetching data from the servers. The billions of resource records in the DNS directory are split into millions of files called zones. Zones are kept on authoritative servers distributed all over the Internet, which answer queries according to the DNS network protocols. In contrast, caching servers simply query the authoritative servers and cache any replies. Most servers are authoritative for some zones and perform a caching function for all other DNS information. Most DNS servers are authoritative for just a few zones, but larger servers are authoritative for tens of thousands of zones.

Before the Internet, ARPANET was a large wide-area network created by the United States Defense Advanced Research Project Agency (ARPA).

The Internet Engineering Task Force is a large open international community of network designers, operators, vendors, and researchers concerned with the evolution of the Internet architecture and the smooth operation of the Internet.

DIN, the German Institute for Standardization, is a registered association, founded in 1917. Its head office is in Berlin. Since 1975 it has been recognized by the German government as the national standards body and represents German interests at international and European level.