1 - Configure a Windows System State backup job. DNS zones stored in Active Directory require a comprehensive system state backup. On a domain controller that is running the DNS service, launch the Windows Server Backup utility from the Start menu by clicking on Start, Accessories, System Tools and "Windows Server Backup."
If Windows displays an error indicating that Windows Server Backup is not installed, open the Server Manager from the Adminsitrative Tools folder, click on "Features" in the tree to the left, and "Add Features" from the links on the right. Scroll to the bottom and click on the check box for "Windows Server Backup Features." Click "Next" and then "Install."
In Windows Server Backup, select "Backup Schedule..." from the list of Actions to the right. Choose "Custom" on the first page of the backup configuration wizard, click "Next" and click on the "Add Items" button. Click the checkbox next to "System state" and click "OK." Click "Next" and select a backup schedule. On the "Specify Destination Type" page of the wizard choose an appropriate destination.
2 - Copy the DNS zone files to a safe location. Locate the DNS zone files in the system root directory by opening File Explorer and drilling down to c:\Windows\DNS\backup. Copy the files in this folder to an alternative location such as a network share.
3 - Back up the Active Directory integrated zone files manually. From the Start menu, right-click on the command prompt icon and select "Run as Administrator" from the context menu. At the command prompt, type "dnscmd /ZoneExport ," replacing "" with the name of the DNS zone as listed in the DNS control panel applet and "" with a name of your choosing. Windows creates this backup file in the directory "c:\Windows\System32\DNS."
Read more: How to Back Up Windows DNS Servers | eHow.com http://www.ehow.com/how_7164013_back-up-windows-dns-servers.html#ixzz2CfUAMKba