This replica is run by the North-American Internet Systems Consortium (ISC), and together with the K server replica (managed by RIPE), the L-root server replica, managed by the Internet Corporation for Assigned Names and Numbers (ICANN), the J-root server replica and the .com and .net replica, all managed by Verisign, DNS response time for queries is improved. This happens thanks to being physically close to each replica. At the same time, security levels increase because global impacts in case of DDoS attacks are minimized.
The Domain Name System (DNS) is an Internet cornerstone based on a hierarchical structure where millions of servers around the world have part of the information to make the system work. The root system consists of 13 servers which are named from A to M. Being equal, 10 are located in the United States, two in Europe and one in Japan. The reduced number of root servers and the high concentration in the USA would lead into a security and stability weakness, especially regarding DDoS attacks, if replicas did not exist.
That’s why managing institutions of some of these 13 servers have replicas distributed around the world to improve the safety and availability of the service.