How often is the time/date updated automatically?

Question

I am running Ubuntu 14.04 32-bit in a VMWare VM. I suspended the VM for a weak and then resumed it. I noticed that the time/date was incorrect, likely due to the fact that it was still set to the time and date when the VM got suspended. However, after a few hours of use the time was still the same. How often does the date/time get checked when Ubuntu is set to do it automatically?

Note: this question was changed from the original which was about setting the date/time. For some reason I was being locked out of manually changing the date/time through the GUI. The button [Unlock to change these settings] that allows a manual change would not unlock. That issue went away.

Answer 1

First of all, this is a must-read for those needing to keep time consistent in VMs:
Timekeeping in Virtual Machines

How often does the date/time get checked when Ubuntu is set to do it automatically?

That depends entirely on how you do it, as there are multiple ways to keep your time in sync:

• ntpdate using cronjob
• ntpd
• VMware tools
• something else that I don't think of right now

I recommend using ntpd. In that case, the poll interval is variable:

By default, ntpd runs in continuous mode where each of possibly several external servers is polled at intervals determined by an intricate state machine. The state machine measures the incidental roundtrip delay jitter and oscillator frequency wander and determines the best poll interval using a heuristic algorithm. Ordinarily, and in most operating environments, the state machine will start with 64s intervals and eventually increase in steps to 1024s. A small amount of random variation is introduced in order to avoid bunching at the servers. In addition, should a server become unreachable for some time, the poll interval is increased in steps to 1024s in order to reduce network overhead.

Source: ntpd manpage