Authoritative DNS Servers
Every organization with publicly accessible hosts ( such as web server and mail several on the internet must provide publicly accessible DNS records that map the names of those hosts to IP addresses. An organization authoritative DNS server house these DNS records. An organization can chosen to implement its own authoritative DNS server to hold these records alternatively the organization can pay to have these records store in an authorities DNS server of some service provide. Most universities and lamp companies implement and maintain their own primary and secondary their own primary and secondary ( backup) authoritative DNS server.