To configure conditional forwarding as an attribute of DNS.

To configure conditional forwarding as an attribute of DNS, complete the following steps:
1. On a Windows Server 2003 domain controller, open the DNS console.
2. Right-click the DNS server you wish to work with and click Properties.
3. Select the Forwarders tab of the DNS properties dialog box for the selected server.
4. Click the New button to the right of the DNS domain list.
5. Enter the domain name for which the conditional forwarders should be configured — for example, sales.company.com — and click OK.
6. Click on the new domain forward that you just added in DNS domains list and type the IP address of the primary DNS server for that domain in the box below, labeled Selected Domains Forwarder IP Address List.
7. Click the Add button.
Once you click OK on the DNS properties dialog box, the conditional forwarder for the domain you specified will be ready to go; however, you may want to restart the DNS service just to make sure everything is working.
Note: For conditional forwarders to work, all the DNS servers in your Active Directory environment must run Windows Server 2003.