I though NTP was a very common thing among server users, yet I could only find a few imprecise answers to my problem.

Well, I just added an NTP server into the NTP field of the System Time page in Plesk control panel. I added it, and in a few seconds my system time get synched with the NTP server. Whenever I change system time to a wrong one, in few the server updates it correctly.

Well, the problem is that when I login to shell, and type service ntpd status, it says "ntpd is stopped" - in other words, while Plesk is synching my server to the NTP server, the Ntpd seems not to be running. Not only that. If I type ntpq -p via shell, in the list of servers there is only LOCALHOST.

My question is: does anybody know if Plesk isn't using the NTPD process to synch the system to the NTP server???

The question comes to me also because, even if I didn't open the port for NTP (37) in APF, the date is correctly updated by Plesk. Is it also possibile Plesk is using 8443 for date update?

I badly need a secure, clear answer from some advanced user... I couldn't find any help in Plesk.com.

Thanks!!!!!

Plesk doesn't run ntpd. The NTP rpm includes a program named ntpdate, which is sort of a client. Plesk runs ntpdate on a schedule, and updates accordingly. I believe it makes an outbound request on port 123, but that's just off the top of my head. Most firewalls are set up to allow outbound requests, so they won't block the client.

Thanks!! You won't believe but nobody was able to answer this question, and Plesk documentation is very lacking in the NTP section. I just wonder how often Plesk updates the time!

It's set up as a cron job (that's how I figured it all out). Do "crontab -l" and you can see the command that's used. I think it updates on the 47th minute of every hour.