Root Hints Files

The root hints file , also called the cache hints file , contains host information that is needed to resolve names outside of the authoritative DNS domains. It contains the names and addresses of root DNS servers.

If your network is connected to the Internet, the root hints file should contain records for the root DNS servers on the Internet. In Windows 2000, a root hints file with current Internet root DNS mappings is installed as the file Cache.dns in the directory % SystemRoot %\System32\Dns.

If your network is not connected to the Internet, you must replace the NS and A records in the cache file with NS and A records for the DNS servers that are authoritative for the root of your private TCP/IP network.

For example, suppose you have created two internal root DNS servers ( and You then create a root hints file on other DNS servers in your network, pointing to the internal root DNS servers. That way, if other name servers receive a query they cannot resolve, they can simply query the internal root servers specified in the file.

The following reskit root hints file provides NS resource records and name-to-IP address mappings for name servers in the domain.

; Internal root hints file for, which is not connected to

; the Internet

. 86400 IN NS

. 86400 IN NS 86400 IN NS 86400 IN NS


The Windows 2000 Configure DNS Server wizard makes a best effort to determine whether the network is connected to the Internet and, if not, creates its own cache file.