you need to do first?

You work as a Network Administrator at AIOTestking.com. AIOTestking.com has an Active Directory
Domain Services (AD DS) domain named AIOTestking.com. All servers in the AIOTestking.com domain
have Microsoft Windows Server 2012 R2 installed.
AIOTestking.com has a main office and a branch office. The two offices are connected by a WAN
link.
A server in the main office named TESTKING-SR21 runs the DNS Server role and hosts an Active
Directory Integrated primary zone for AIOTestking.com. You install a server named TESTKING-SR22
in the branch office. TESTKING-SR22 runs the DNS Server role.
You plan to configure a secondary zone for AIOTestking.com on TESTKING-SR22.
What do you need to do first?

A.
You should modify the AIOTestking.com zone on TESTKING-SR21 to be a non-Active Directory
Integrated primary zone.

B.
You should log in to TESTKING-SR21 and configure an MX record for TESTKING-SR22.

C.
You should log in to TESTKING-SR21 and configure a zone delegation for TESTKING-SR22.

D.
You should log in to TESTKING-SR21 and in the properties of the AIOTestking.com zone, add
TESTKING-SR22 as a name server.