System Time III

System Time III


Synchronizing Time with NTP 


The key problem with using netdate in a cron job to keep time synchronized is the fact that netdate
adjusts the time abruptly. It doesn’t gradually adjust time to reach a point of synchronization.
Whatever time it is on the time server is the time the system time on the local system is set to.
In addition, netdate may adjust the time backward and forward, depending on how your local
system clock has drifted. This really messes up timestamps on your local files and can cause some
Linux services to completely freak out.



A better option for network time synchronization is to use the Network Time Protocol (NTP)
to sync time with a network time provider. NTP manages time in a much cleaner fashion than
netdate. NTP adjusts time in a much gentler manner. If there is a time differential between the
time provider and the time consumer (your local system), it adjusts time gradually in small increments
until time is eventually synchronized.



NTP is also widely supported by most operating systems. The netdate option only works 
with the time service on a Linux/UNIX time provider. NTP, on the other hand, allows time to 
be synchronized among systems in a heterogeneous network environment. It’s supported by the
following operating systems:



• Linux
• Windows
• OSX
• UNIX



NTP is a little more complex than netdate. Therefore, to implement NTP, you need to be
familiar with the following:



• How NTP works
• Configuring NTP








LX0-104 Exam Objectives (N)