Double-Take Software

Much to the chagrin of Mr. Ballmer in Redmond, not everyone uses the Microsoft Active Directory Integrated DNS (AD DNS) system just yet.  While certain applications like Microsoft Exchange Server are designed to work with AD DNS, they can work with other forms of DNS as well.  Many other applications are not particular about which DNS systems they use, as long as a standards-based DNS server is available to accept their requests.

Double-Take Availability’s Application Failover module has had the ability to update AD DNS servers as part of an automated failover routine since way back when it was introduced as the DTAM wizard.  The issue has always been that while many clients use Application Failover for SQL, File, Exchange, Blackberry and SharePoint servers; many of those do not use AD DNS in their environment.

To help with this, the Application Failover wizard can utilize a command-line switch to keep the wizard from trying to find, verify and update an AD DNS server if none is present in the environment. However, customers don’t always know that the tool exists, or how to use it.

The easiest way to use the AltDNS tool is to create a new shortcut for the Application Manager (you’ll find the icon under Start|Programs|Double-Take) and adding /AltDNS to the end of the command line that shows up in the “Target” field of the shortcut’s properties page.  You could also run the executable from the command-line with the /AltDNS switch, but you will then have to remember to do that each time.

You will not see any major differences between running the software with and without the switch right up front.  The wizards look about the same, though of course you cannot use the DNS failover components in the Options area of the system.  What you will notice is that the wizard will not check for any of the DNS components during the server identification routines, and will not list any warnings dealing with DNS during the validation run. 

This doesn’t mean we cannot update other DNS systems, it just means that we do not look for an AD DNS controller to update.  If you modify the failover and failback scripts via the Advanced tab in the options pages, you can add in command-line operations to update your DNS controllers.  This means you will need to grant our services permission to update those records manually, and you will need to find the right commands to issue and to put in the scripts themselves.  If you find you need assistance, our Professional Services team can help with DNS configurations on a per-engagement basis.

The /AltDNS feature set is only available on our Application Manager (formerly DTAM) wizard.  FSFO, Hyper-V failover and other wizards can still be configured at the script-level, but will always check for an AD DNS controller and warn you if they cannot find one in the environment.

Thanks to Nick R. for this week’s question!