Config:

/etc/ntp.conf

Commands:

ntptrace                  #Show sync stats
watch -n1 -d ntptrace     #Show continiously sync stats
ntpq -p                   #NTP query program
ntpq -pn                  #NTP query program. showing IP instead of DNS name

“offset”:

Shows timedifference between reference time (timeserver) and system time

“jitter”:

Gibt die Größenordnung der Schwankungen zwischen einzelnen Zeitvergleichen an.

Check from a Linux-Client:

vi /etc/ntp.conf          #Select NTP-server you want to check
date -s "1974-01-04"
date --set="2 OCT 2006 18:00:00"
date +%T -s "20:46:05"
service ntpd restart
systemctl restart ntpd.service
date
timedatectl set-timezone Europe/Berlin
timedatectl 
dpkg-reconfigure tzdata