Configure NTP to get the time from systems that are available from 1)
internet, 2) inside corporate firewall, 3) inside corporate external
lab firewall and 4) timeserver of DSL provider.
To the file /etc/ntp/steptickers add the one very long line:
harbor.ecn.purdue.edu tick.mit.edu ntp01.cca.cpqcorp.net ntp02.cca.cpqcorp.net alpha1.ispworks.com shell.mv.net
Turn ntp on at boot time:
chkconfig --level 45 ntpd on