1 Add all xenserver Public NTP servers to the host . Refer below link for the same.
Note: Make sure that you have identical and equal number of NTP source servers on all xenserver host in pool
2. It will automatically restart the ntpd/chronyd service but sometimes that does not sync the time to NTP and we have to manually restart the ntpd/chronyd service using below command.
# service ntpd restart
Run below command to restart chronyd service
# systemctl restart chronyd.service
If even after manually restarting the service it does not work then follow below steps
3. Stop ntpd service using below command
# Service ntpd stop
Run below command for chronyd service
# Systemctl stop chronyd.service
4. Manually sync xenserver from hwclock to desired ntp servers using below command
# ntpdate 0.xenserver.pool.ntp.org
Use below command for Citrix Hypervisor 8.1 and 8.2
# chronyd -q 'server 0.xenserver.pool.ntp.org iburst'
5. Started ntpd service
service ntpd start
It will Sync the host to NTP servers now.
Use below command to start chronyd service
systemctl start chronyd