A. An RODC that's a DNS server should point to itself for the primary DNS server. DNS servers in a hub location should be the secondary/alternate DNS servers. By default, when you promote a RODC that's a DNS server, the RODC adds itself at the end of the alternate DNS server list as You should modify this manually or via Group Policy after creation.

Related Reading:

Check out hundreds more useful Q&As like this in John Savill's FAQ for Windows. Also, watch instructional videos made by John at ITTV.net.