Hi, 2009/3/15 mcclnx mcc <mcclnx at yahoo.com.tw>: > I just setup CENTOS 4.7 with latest patches on DELL server. > I also configured NTP point to out time server. I found > /var/log/messages file every 20 to 30 minutes will generate > a error message : > Mar 15 14:28:15 SER1 ntpd[25037]: sendto(172.29.21.16): Invalid argument I saw this once when I changed a machine's IP but did not restart the NTP service. The daemon was still trying to send/receive packets using the old IP. After restarting NTP (service ntpd restart) the problem was fixed. Make sure you also check that NTP is properly synchronizing the clocks with the "ntpq -p" command. HTH, Filipe