我已经在 CentOs 安装上配置了 ntpd ，使用简单的 /etc/ntp.conf ，只有 3 行：
server 0.pool.ntp.org
server 1.pool.ntp.org
server 2.pool.ntp.org
server 192.168.1.1
不幸的是，无论我运行什么主机，我都无法让 ntpdate 与外部服务器正确同步。这是我运行时得到的调试输出：
[root@myhost superuser]# ntpdate -d pool.ntp.org
3 May 12:23:31 ntpdate[3912]: ntpdate 4.2.4p8@1.1612-o Fri Feb 22 11:23:28 UTC 2013 (1)
Looking for host pool.ntp.org and service ntp
host found : 173.44.32.10
transmit(173.44.32.10)
transmit(69.41.163.31)
transmit(18.85.44.118)
transmit(65.182.144.36)
transmit(173.44.32.10)
transmit(69.41.163.31)
transmit(18.85.44.118)
transmit(65.182.144.36)
transmit(173.44.32.10)
transmit(69.41.163.31)
transmit(18.85.44.118)
transmit(65.182.144.36)
transmit(173.44.32.10)
transmit(69.41.163.31)
transmit(18.85.44.118)
transmit(65.182.144.36)
transmit(173.44.32.10)
transmit(69.41.163.31)
transmit(18.85.44.118)
transmit(65.182.144.36)
173.44.32.10: Server dropped: no data
69.41.163.31: Server dropped: no data
18.85.44.118: …