Your network consists of an Active Directory forestthat contains one domain.
All domain controllersrun Windows Server 2008 R2and are configured as DNS servers.
You have an Active Directory-integrated zone.
You have two Active Directory sites.
Each site contains five domain controllers.
You add a new NS record to the zone.
You need to ensure that all domain controllers immediately receive the new NS record.
What should you do?

A.
From the DNS Manager console, reload the zone.

B.
From the DNS Manager console, increase the version number of the SOA record.

C.
From the command prompt, run repadmin /syncall.

D.
From the Services snap-in, restart the DNS Serverservice.

Explanation:
http://technet.microsoft.com/en-us/library/cc835086%28v=ws.10%29.aspx
Repadmin /syncall
Synchronizes a specified domain controller with allof its replication partners.
http://ivan.dretvic.com/2012/01/how-to-force-replication-of-domain-controllers/
How to force replication of Domain Controllers
From time to time its necessary to kick off AD replication to speed up a task you may be doing, or just a good
too to check the status of replication between DC’s.
Below is a command to replicate from a specified DCto all other DC’s.
Repadmin /syncall DC_name /APed
By running a repadmin /syncall with the /A(ll partitions) P(ush) e(nterprise, cross sites) d(istinguished names)
parameters, you have duplicated exactly what Replmon used to do in Windows 2003, except that you did it in
one step, not many.And with the benefit of seeing immediate results on how the operations are proceeding.
If I am running it on the DC itself, I don’t even have to specify the server name.