# hwclock --systohc --localtime
You update your system time from ntp but sometimes, somehow, something happens and it can not sync to hardware clock as it should be and after reboot, you will need ntp again (with an internet connection).
This is a solution to sync ntp clock to BIOS but be aware that, your BIOS clock will need sync in 24 hours but if you do do not care about seconds, it will carry you along.
If you care about microseconds, hehe
welcome...