Select a machine for the centos Intranet. If the machine cannot connect to the Internet: 1. Set the correct time zone and time zone for the machine: cp/usr/share/zoneinfo/Asia/Shanghai/etc/localtime or ln-sf/usr/share/zoneinfo/Asia/Shanghai/etc/localtime, set date 010318242008 (month, day, and year) (complete writing) 2. Set the hardware time so that the system time set above can be connected to the Internet through hwclock -- systohc: 1. cp/usr/share/zoneinfo/Asia/Shanghai/etc/localtime or ln-sf/usr/share/zoneinfo/Asia/Shanghai/etc/localtime ntpdate pool.ntp.org 2. hwclock -- Systohc then, enable the ntp server installation service on this machine: yum-y install ntp start: chkconfig ntpd on start service: service ntpd start other machines in the Intranet that cannot connect to the Internet, the time on the ntp server is accurate. Scheduled time: # crontab-e // enable linux scheduled task 0 23 ***/usr/sbin/ntpdate 210.72.145.44 // The time format is as follows: if the value of 23 is changed to 0-23/2, it indicates that *** is executed every two hours. | + -- Year (range: 1900-3000) | + ---- Day of the Week (range: 1-7, 1 standing for Monday) | + ------ Month of the Year (range: 1-12) | + -------- Day of the Month (range: 1-31) | + ---------- Hour (range: 0-23) + ------------ Minute (range: 0-59) // Add this Line Information. The ip address can be specified as the IP address of the machine on which the ntp server is configured. The above command sets the storage disk. #/Sbin/service crond reload // reload linux scheduled tasks