1. 修改注册表项
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\NtpServer
Enabled 设定为 1（默认0）
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Config\
AnnounceFlags 设定为 5 （默认 10）
| Value | Meaning |
|---|---|
| 0 | Timeserv_Announce_No, Reliable_Timeserv_Announce_No. The domain controller does not advertise time service. |
| 1 | Timeserv_Announce_Yes. The domain controller always advertises time service. |
| 2 | Timeserv_Announce_Auto. The domain controller automatically determines whether it should advertise time service. |
| 4 | Reliable_Timeserv_Announce_Yes. The domain contoller will always advertise reliable time service. |
| 8 | Reliable_Timeserv_Announce_Auto. The domain controller automatically determines whether it should advertise reliable time service. |
2. 禁用防火墙或设置例外，UDP 123端口。
3. 运行 services.msc，将Windows Time服务设置成
自动（延迟启动）
Win7下如果设置成自动，下次重启后此服务会被停止，原因不详。
经实验，延迟启动也并不需要用户登录即可启动。
4. 重启动校时服务：net stop w32time && net start w32time
网络设备（如cisco、h3c交换机……）不能正常同步NTP服务器时间：
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Config\LocalClockDispersion
值修改为0 （默认为0x0000000a）
转自：http://blog.sina.com.cn/s/blog_671c54fe0102v4wy.html