We have several CENTOS 4 and 5 servers. ALL CENTOS servers have NTP setup to sync time server. Several days ago due to power outage all servers are reboot. Due to DNS server did NOT up quickly, CENTOS servers start up and can NOT find time server.

For CENTOS 5.X servers, it did quickly resync to time server after 30 minutes.

For CENTOS 4.X servers, it have been 3 days still NOT sync to time server. I know I can run "service ntpd restart" to force server sync to time server, but I like to know how long it take for CENTOS 4.X automatic resync to time server.

man ntpd: excerpt: Most operating systems and hardware of today incorporate a time-of-year (TOY) chip to maintain the time during periods when the power is off. When the machine is booted, the chip is used to initialize the operating system time. After the machine has synchronized to a NTP server, the operating system corrects the chip from time to time. In case there is no TOY chip or for some reason its time is more than 1000s from the server time, ntpd assumes something must be terribly wrong and the only reliable action is for the operator to intervene and set the clock by hand. --- end excerpt ---

mark