REFERENCE

DNS Root Nameservers

The Internet root servers are the backbone of the Domain Name System (DNS), which is the system that maps human-readable domain names (such as www.example.com) to machine-readable IP addresses (such as 192.0.2.1). These name servers are a network of 13 authoritative servers that provide the top-level hierarchy of the DNS and are deployed around the world at 1548 sites.