Ntpdate not updating clock
They are already commented out by default on Cent OS/RHEL 6. The Raspberry Pi does not have a RTC (Real Time Clock) module and it is not able to keep the date and time without a power source.
This is all well and good, but what happens if there is a partial outage within one's organization that prevents access to the local NTP servers?
If your Raspberry Pi is not connected to the Internet, you are out of luck and the only option is to buy and install an RTC module.