time settings of domain controller

dear all

this is the time settings of my  2 domain controller  server

Value Name                 Value Type          Value Data
------------------------------------------------------------

ServiceDllUnloadOnStop     REG_DWORD           1
ServiceMain                REG_SZ              SvchostEntry_W32Time
ServiceDll                 REG_EXPAND_SZ       C:\Windows\system32\w32time.DLL
Type                       REG_SZ              NT5DS


Value Name                 Value Type          Value Data
------------------------------------------------------------

ServiceDllUnloadOnStop     REG_DWORD           1
ServiceMain                REG_SZ              SvchostEntry_W32Time
ServiceDll                 REG_EXPAND_SZ       C:\Windows\system32\w32time.DLL
Type                       REG_SZ              NT5DS


I know that NT5DS type  means that The domain controller  is configured to use the domain hierarchy
for its time synchronization  but I can not understand what that  means could any one explains it to me in a simpler way
another question
is this the right type for the DC  that all pc in the domain should synchronize with


I have another question I have two domain controllers in on single site ,what is the best way of  configuring  time setting on both servers so that all pc
that are part of domain can rely on these domain controller to sync time with