Originally Posted by aga_nima
I was wondering how I can run ntp on my server every 5 minutes. I looked into ntpd, but was not very helpful
I think there's some basic misunderstanding of how ntp is intended to be used in this thread. You don't tell ntp to sync every x minutes. You run the ntpd-daemon continously and let the daemon keep the clock in sync.
The daemon is configured to use several (five is a good starting point) time sources. The daemon decides for itself (within some limits) how often each source should be polled.
There's a ton of info written on this subject. Google is your friend...