Root hints are responsible for forwarding unresolved DNS queries to other DNS server authoritative for that domain. Our DNS server must know the IP address of servers which will forwards DNS queries to other DNS servers.
Root hints are used to locate other DNS Servers on the Internet that are authoritative for DNS domain namespace.
CACHE.DNS file consists of server addresses which point to the top level DNS servers on the Internet. This file can be found in the %systemroot%\system32\dns\samples folder.
Microsoft automatically loads this file when configuring DNS Server on Windows Server 2003.
