It seems that having the time update when resuming a VirtualBox VM from a paused state is not possible.I've reached this conclusion after reading online for a few days and trying many different things, but notably putting tinker panic 0 in the [/etc/ntp.conf] file.  I restarted the ntpd service afterwards and then proceeded to test it by pausing the machine state for a few minutes and then resuming.  The time picked up where it left off (and didn't sync).Many people have asked this question before but they seem to all morph into some, ever-so-slightly, different variation.NTP not syncing in a VMhttps://stackoverflow.com/questions/14629704/ntp-client-undisciplined-local-clock/14634941#14634941https://serverfault.com/questions/686087/ntp-running-server-time-is-wrong-on-vmMy Guest in the VM: CentOS Linux release 7.3.1611[root@CentOS7 ~]# systemctl list-unit-files ntpd*UNIT FILE       STATEntpd.service    enabledJust in case anyone is wondering, I did disable the chrony services so there wouldn't be any conflicts because I prefer NTPD due to available documentation.[root@CentOS7 ~]# systemctl list-unit-files chron*UNIT FILE              STATEchrony-dnssrv@.service staticchrony-wait.service    disabledchronyd.service        disabledchrony-dnssrv@.timer   disabledAnyone have any last suggestions before I consider a cronjob?  While definitely not optimal it would at least work.== Change of strategy - attempting to use Guest additions to sync time from host ==So I followed advice to install the Guest Additions iso in VirtualBox.  Surprisingly ran into a problem there.Unable to insert the virtual optical disk C:\Program Files\Oracle\VirtualBox\VBoxGuestAdditions.iso into the machine Centos.Could not mount the media/drive 'C:\Program Files\Oracle\VirtualBox\VBoxGuestAdditions.iso' (VERR_PDM_MEDIA_LOCKED).Result Code: E_FAIL (0x80004005)Component: ConsoleWrapInterface: IConsole {872da645-4a9b-1727-bee2-5585105b9eed}Callee: IMachine {b2547866-a0a1-4391-8b86-6952d82efaa0}The fix to that was to launch my Centos desktop GUI where I saw the ISO.  I right-clicked, clicked Open with run software and it installed successfully.  It is still not synching the time though, even after disabling ntpd.So I found this thread:https://www.virtualbox.org/ticket/15179Start the VBoxService process with verbose output on a terminal:/usr/sbin/VBoxService -fvvvThis resulted in:00:00:00.010360 timesync vgsvcTimeSyncWorker: Host:    2017-02-11T21:39:17.257000000Z    (MinAdjust: 100 ms)00:00:00.010428 timesync vgsvcTimeSyncWorker: Guest: - 2017-02-11T21:30:01.781953000Z => 555 475 047 000 ns drift00:00:00.010491 timesync vgsvcTimeSyncAdjust: adjtime by 555 475 047 000 nsbut it didn't actually adjust the time, or maybe that means it's adjusting it in nanoseconds which will take FOREVER. Hmmm...As a last resort I tried:/usr/sbin/VBoxService -fvvv --timesync-set-on-restore 1I think I've wasted enough time on this.  I'll try a cronjob with ntpd -g.
NTP not syncing time even with `tinker panic 0` in /etc/ntp.conf in Centos 7.3 -Resuming VM from paused state
centos;virtualbox;ntp;ntpd
It is possible to sync time from the host using VirtualBox Guest Additions, which came with my VirtualBox 5.1.14.  See my edited question with more info about working through the errors while trying to install Guest Additions.The Grand Finale of my answer:I tried to make it a systemctl service but it kept throwing errors so I put this in my .bashrc file:/usr/sbin/VBoxService --timesync-set-on-restore 1 --timesync-set-threshold 5000 > /dev/nullIt works very well and does what it's supposed to.  