[CentOS] ntp will not drift to correct time

Hi

On 5.3 i have a situation where some boxes have been 3 or 4 seconds out and restarting ntpd has fixed the issue.

What i dont understand is why the clocks did not drift to the correct time when the config seems correct in that restarting ntp did correct the time.

Is there something 'special' i need to do in order for the drift to work?

$ cat /etc/ntp.conf restrict default ignore restrict 127.0.0.1 restrict 10.0.0.0 mask 255.0.0.0 nomodify notrap server server01 server server02 fudge 127.127.1.0 stratum 10 driftfile /var/lib/ntp/drift broadcastdelay 0.008 keys /etc/ntp/keys

# cat /etc/ntp/step-tickers server01 server02

any clues?

thanks