Your network contains an Active Directory domain. The domain contains eight domain
controllers.
You need to verify that all the domain controllers can connect to the time server.
Which command should you run?
A.
netdom.exe query fsmo
B.dcdiag.exe /e /test:Topology
C.repadmin.exe /showrepl *
D.dcdiag.exe /a
Form the below link , id say D
http://blogs.technet.com/b/askds/archive/2011/03/22/what-does-dcdiag-actually-do.aspx
This test validates that the public DsGetDcName function used by computers to locate domain controllers will correctly locate any DCs specified with in the command line with the /s, /a, or /e parameter. It checks that the server successfully reports itself with DS_Flags for:
•DC
•LDAP server
•Writable or Read-Only DC
•KDC
•Time Server
•GC or not (and if claiming to be a GC, if the is GC ready to respond to requests )