DNS root zone

In computing and the Internet, the DNS root zone is the top-level DNS zone in the hierarchical namespace of the Domain Name System (DNS). Before October 1, 2016, the root zone had been overseen by the Internet Corporation for Assigned Names and Numbers (ICANN) which delegates the management to a subsidiary acting as the Internet Assigned Numbers Authority (IANA). Distribution services are provided by Verisign. Prior to this, ICANN performed management responsibility under oversight of the National Telecommunications and Information Administration (NTIA), an agency of the United States Department of Commerce. Oversight responsibility transitioned to the global stakeholder community represented within ICANN's governance structures. A combination of limits in the DNS definition and in certain protocols, namely the practical size of unfragmented User Datagram Protocol (UDP) packets, resulted in a practical maximum of 13 root name server addresses that can be accommodated in DNS name query responses. However, as of 2007, the root zone was serviced by several hundred servers at over 130 locations in many countries.