When you install Microsoft DNS server, the cache file is automatically installed from the product disk. The data in this file contains name-to-IP address mappings for the InterNIC root domain name servers. Microsoft DNS server uses this information when name resolution queries must be resolved by getting information from name servers outside the local enterprise by contacting name servers on the Internet. You should not change this file unless the name-to-IP address mappings of the Internet root servers change.
If the computer on which you install Microsoft DNS server does not connect to the Internet, you should delete all the entries in this file and replace them with NS and A records for your intranet root name servers.