NTP Date
NTP is Network Time Protocol. This is used for syncing a OS to a time server.
In Linux you'd type:
ntpdate time-nw.nist.gov
if you get an error that is doesnt know the command you will need to install ntp
yum -y install ntp
or
apt-get install ntp
In Windows there is not a direct executable. however you can:
Click on your clock in your task bar
click change time date
Click the Internet Time tab.
you will see an Update now button.
For Automation of set time through a cron job:
Update the server time ever hour at :30 and send an email
30 * * * * ntpdate time-nw.nist.gov
Update the server time ever hour at :30 and send no email
30 * * * * /usr/sbin/ntpdate time-nw.nist.gov > /dev/null 2>&1
Update the server time ever hour at :30 and send email if error
30 * * * * /usr/sbin/ntpdate time-nw.nist.gov > /dev/null
Setting the timezone CentOS: