How to change the time server for the _in built_ internet time in ubuntu 16.04 LTS?
Ubuntu 16.04 uses by default server ntp.ubuntu.com
[reference].
To change the default server, edit the config file with an editor:
sudo vi /etc/systemd/timesyncd.conf
Uncomment the NPT=
line and define the server you want to be used instead of default:
[Time]
NTP=some.ntp.server.com
To "audit" the time-synchronization events and verify the server that was contacted, use the following command:
cat /var/log/syslog | grep systemd-timesyncd
According to the official documentation at: https://help.ubuntu.com/lts/serverguide/NTP.html
The nameserver to fetch time for timedatectl and timesyncd from can be specified in /etc/systemd/timesyncd.conf and with flexible additional config files in /etc/systemd/timesyncd.conf.d/.