Configure a time source / NTP on Centos

We should firstly install the necessary packages:

yum install ntp ntpdate ntp-doc

And ensure the service is enabled:

systemctl enable ntpd

Configure the relevent NTP server:

interface ignore wildcard
interface listen 127.0.0.1
interface listen ::1
server 0.centos.pool.ntp.org iburst
server 1.centos.pool.ntp.org iburst
server 2.centos.pool.ntp.org iburst
server 3.centos.pool.ntp.org iburst

And finally start the service:

service ntpd start