Assign a Conditional Forwarder for a Domain Name
Updated: May 9, 2008
Applies To: Windows Server 2008
A conditional forwarder is a Domain Name System (DNS) server on a network that you use to forward DNS queries according to the DNS domain name in the query. For example, you can configure a DNS server to forward all the queries it receives for names ending with widgets.contoso.com to the IP address of a specific DNS server or to the IP addresses of multiple DNS servers.
You can use this procedure to designate a conditional forwarder using the DNS Manager snap-in.
Membership in the Administrators group, or equivalent, is the minimum required to complete this procedure. Review details about using the appropriate accounts and group memberships at Local and Domain Default Groups (http://go.microsoft.com/fwlink/?LinkId=83477).
Open DNS Manager. To open DNS Manager, click Start, point to Administrative Tools, and then click DNS.
In the console tree, double-click the applicable DNS server. Expand DNS, and then double-click Applicable DNS server.
In the console tree, click Conditional Forwarders, and then on the Action menu, click New conditional forwarder.
In DNS domain, type the fully qualified domain name (FQDN) of the domain for which you want to forward queries.
Click the IP addresses of the master servers list, type the IP address of the server to which you want to forward queries for the specified DNS domain, and then press ENTER.
- You can use the Up and Down buttons next to the IP addresses of the master servers list to change the order in which forwarders are queried.
By default, the DNS server waits five seconds for a response from one conditional forwarder IP address before it tries another forwarder IP address. In Number of seconds before forward queries time out, you can change the number of seconds that the DNS server waits. When the server has exhausted all forwarders, it attempts standard recursion.
- You can disable recursion for the DNS server so that it will not perform recursion on any query. If you disable recursion on the DNS server, you will not be able to use forwarders on the same server.
- Do not enter a forwarder's IP address more than once in a DNS server's forwarders list because it is a more reliable or geographically closer server. If you prefer one of the forwarders, put that forwarder first in the series of forwarder IP addresses.
You can prevent common problems that are associated with forwarders by configuring your DNS servers to avoid overusing your forwarders.