Which protocol should you allow on the firewall?

Your network contains an internal network and a perimeter network.
The networks are separated by a firewall. The internal network contains a Central Management Server.
The perimeter network contains an Edge Server. You discover that changes to the Central Management Store (CMS) do not replicate to the Edge Server.
You need to ensure that all changes to the CMS replicate to the Edge Server.
Which protocol should you allow on the firewall?

A.
HTTPS

B.
PSOM

C.
STUN

D.
TURN

Explanation:
http://technet.microsoft.com/en-us/library/gg425891.aspx

http://blogs.technet.com/b/jenstr/archive/2010/10/13/what-is-central-management-store-cms.aspx