Anybody Got the Time?
A friend of mine recently was complaining about a lengthy network management job he ran one night that was supposed to update the NT system software on a group of his company’s PCs. He alerted the users that would be affected that the job would run that evening. He asked them to leave their PCs on when they left the office and promised the whole thing would be over before they returned to work the next day. He carefully triggered the event for execution at midnight that night and went home expecting it all to be done by the next day.
The next morning, to his surprise, he discovered that only half the PCs in the target group ran the job he scheduled. Before long, irate users began calling him to complain that his job suddenly started running during the day. This went on for several days. His carefully scheduled job ran at apparently random times.
The cause, as it turned out, was simple: Midnight on the PC he used to schedule the job and midnight on the affected users’ PCs turned out to be different times. A quick survey revealed the clocks on the company’s PCs were anywhere from several minutes to several hours out of sync, and in some cases even days.
Could this happen to you? The bad news is it can. The good news is that Windows NT comes equipped with almost everything you need to prevent it. You can synchronize the clocks of all of your Windows NT clients and servers by following four steps.
Start by picking a master clock you can use to synchronize everyone with. If you’re part of a large corporation, chances are good there is already a network time protocol (NTP) server somewhere in your intranet that you can use. Otherwise, consider synchronizing with a public NTP server or to the U.S. government’s National Institute for Standards in Technology (NIST). You’ll find plenty of references for these sources at the University of Delaware's Web site: www.eecis.udel.edu/~ntp/.
Next, get a copy of the Windows NT Resource Kit. Install the package’s TimeServ.exe utility on two or three Windows NT primary clock servers in your network, and use it to synchronize their clocks with your preselected master clock. You can find more information about TimeServ at www.niceties.com/TimeServ.html.
Then install TimeServ.exe on all Windows NT domain controllers configured to synchronize their clocks with your primary clock servers. The TimeServ documentation explains how to do this.
Finally, insert the command "NET TIME %LOGONSERVER% /SET /Y" into your domain’s logon scripts. Thereafter, as users log on their PC clocks will be in sync with the corresponding domain controller’s clock.
But what if you can’t get through your firewall to a public NTP server, or to NIST? If you have the bucks, check out TrueTime at www.truetime.com. They sell a turnkey NTP server that synchronizes itself to satellites and feeds it through an Ethernet network to your TimeServ-equipped NT servers.
What’s that you say? You’d like to synchronize the clocks on your non-Windows computer systems with your NT systems? There are links on the University of Delaware’s Web site to downloadable shareware that can convert Windows NT servers into standard NTP servers.
There’s no excuse. If you envision your computer network as a single system of distributed computers working together, then you owe it to yourself to use some of these techniques to ensure that your system is tuned to a single clock. --Al Cini is a senior consultant with Computer Methods Corp. (Marlton, N.J.) specializing in systems and network integration. Contact him at email@example.com.