Windows Time Service Tools and Settings:
http://technet.microsoft.com/en-us/library/cc773263.aspx

> W32tm /query /configuration

How the Windows Time Service Works:
http://technet.microsoft.com/en-us/library/71e76587-28f4-4272-a3d7-7f44ca50c018


You can run the command:
> reg query HKLM\SYSTEM\CurrentControlSet\Services\W32Time\Parameters
and read the value of NtpServer in the command output.


    ServiceDll    REG_EXPAND_SZ    %systemroot%\system32\w32time.dll
    ServiceMain    REG_SZ    SvchostEntry_W32Time
    ServiceDllUnloadOnStop    REG_DWORD    0x1
    Type    REG_SZ    AllSync
    NtpServer    REG_SZ    time.consona.net,0x9

    ServiceDll    REG_EXPAND_SZ    %systemroot%\system32\w32time.dll
    ServiceMain    REG_SZ    SvchostEntry_W32Time
    ServiceDllUnloadOnStop    REG_DWORD    0x1
    Type    REG_SZ    NT5DS
    NtpServer    REG_SZ    time.windows.com,0x9