ntpdate problem

[Антон Клесс]

I have the following line in my root cron:

5 * * * * /usr/sbin/ntpdate ru.pool.ntp.org > /dev/null

That must hourly adjust system time via NTP.
But I discover that it works from time to time: some days just once, some
days 5-6 times a day I receive e-mail with text like

12 Mar 12:05:05 ntpdate[25368]: no server suitable for synchronization found


But if I log in to server and run

# /usr/sbin/ntpdate ru.pool.ntp.org

everything always works OK: it says

12 Mar 13:51:57 ntpdate[27256]: adjust time server 80.93.56.210 offset
-0.616000 sec


Maybe NTP server doesn't like when some client (my server) asks it such way
- once a hour in same minute - and blocks my queries?

Any suggestions?