How can I prevent a second network interface from updating DNS with its IP address?

Recently I added a second network interface to my Domain Controller, and assigned a private subnet to provide a iSCSI volume for backups, but the IP address from this interface is being propagated to my DNS server.

So now, when I use nslookup against my domain, one of the responses is this private IP address.

How can I prevent this interface from updating DNS with its IP address?

This is a Windows Server 2012 R2 Domain Controller that's virtualized through XenServer 6.2 SP1.

In the network adapter's advanced DNS properties, clear the check in the box for Register this connection's addresses in DNS.

The location of that setting is about 3/4 of the way down the page here: http://technet.microsoft.com/library/dd163570.aspx