Your network contains an Active Directory forest. All domain controllers run Windows Server 2008 R2 and are configured as DNS servers. You have an Active Directory-integrated zone for contoso.com. You have a UNIX-based DNS server. You need to configure your Windows Server 2008 R2 environment to allow zone transfers of the contoso.com zone to the UNIX-based DNS server. What should you do in the DNS Manager console（）

A. Disable recursion.
B. Create a stub zone.
Create a secondary zone.
D. Enable BIND secondaries.