Steps
Network
Time
Time Zone
Set correct TIMEZONE
mv /etc/localtime /etc/localtime.`date +%Y%m%d`
ln -s /usr/share/zoneinfo/Europe/Amsterdam /etc/localtime
NTP
In the NTP network time protocol configuration file, set the server with the following name:
/etc/ntp.conf
server 0.rhel.pool.ntp.org
server 1.rhel.pool.ntp.org
server 2.rhel.pool.ntp.org
OS upgrade
yum upgrade
Choose y for all