It can take up to 30 minutes before ntpd will start serving requests to clients.
Firstly check the appropriate log files and make sure you have a running server.
Then run 'ntpq -p' to make sure your server is syncing with the external servers, output should look something like this
Code:
[root@pc2 /home/madluther]# ntpq -p
remote refid st t when poll reach delay offset jitter
==============================================================================
time-a.nist.gov .ACTS. 1 u 62 64 3 37.807 -19127. 13.569
time-b.nist.gov .ACTS. 1 u 62 64 3 33.975 -19131. 12.807
tick.usno.navy. 0.0.0.0 16 u - 64 0 0.000 0.000 4000.00
The above illustrates two working servers and one that is not syncing. (A jitter of 4000 indicates there is no sync established)
Once you have a running server try the ntpdate -q localhost command