Managing Root Hints

Applies To: Windows Server 2008

Root hints are Domain Name System (DNS) data stored on a DNS server that identifies the authoritative DNS servers for the root zone of the DNS namespace. You can use root hints to configure servers that are authoritative for nonroot zones so that they can discover authoritative servers that host domains at a higher level or in other subtrees of the DNS domain namespace. These root hints are essential for servers that are authoritative at lower levels of the namespace when they attempt to locate other servers under these conditions.

For example, suppose that a DNS server (Server A) receives a query for an external domain, such as the domain. Server A needs some assistance to locate an authoritative server (such as Server B) for this domain.

For Server A to find Server B—or any other servers that are authoritative for the domain—Server A must be able to query the root servers for the DNS namespace. The root servers can then refer Server A to the authoritative servers for the com domain. The servers for the com domain can, in turn, offer referral to Server B or other servers that are authoritative for the domain. The root hints that Server A uses must have helpful hints to the root servers for this process to locate Server B (or another authoritative server) as intended.

To configure and use root hints correctly, first answer the following questions about your DNS server:

  • Are you using DNS on the Internet or on a private network?

  • Have you deployed your own private root zone?

By default, the DNS Server service is configured with a set of standard root hints. The default root hints contain the name server (NS) and host (A) resource records for the Internet root servers. If, however, you are using the DNS Server service on a private network, you can replace the default root hints with records that point to your own internal root DNS servers.

If a DNS server is configured to access other DNS servers, such as through a list of DNS servers that is configured in its client TCP/IP properties for an installed network connection, the DNS Server service is capable of gathering its own root hints during new server configuration. You can use the Configure a DNS Server Wizard to accomplish this.

To complete this task, perform the following procedure: