Having consumed a lot of my own energy (and that of others, for which I apologize), I think I understand this subject reasonably well from the end-user's point of view. So here's what I learned, in a form that someone might want to put in a FAQ: Q. My computer clock is drifting and doesn't keep accurate time. What can I do about it? A. First, edit (as root) the file /etc/ntp.conf. In the section with the comment "Outside source of synchronized time", add the following servers (with no comment delimiters): server 0.pool.ntp.org server 1.pool.ntp.org server 2.pool.ntp.org server pool.ntp.org If you go to http://ntp.isc.org/bin/view/Servers/NTPPoolServers, you'll be able to improve on these by locating time servers that are specific to your region. Also, check that the drift file, specified later in ntp.conf, is at /var/lib/ntp/drift/ntp.drift. You'll find it useful for checking purposes to know that. In older systems the drift file was at /etc/ntp.drift, and its location may change again. Next, go into Yast System/System Services (Runlevel) and set the entry for ntp to Yes. That ensures that the time daemon ntpd is running and that it will be started when you reboot your system. To check that everything is working, issue the command "ps -A | grep ntp". You should see an indication that ntpd is running. Wait for at least an hour, then do "ls -l /var/lib/ntp/drift/ntp.drift", or wherever the drift file is located. You should see that the drift file has been updated within the last hour or so. If your clock is really far off from the correct time and isn't being corrected, you may need to delete the drift file. ntpd will reconstruct it for you. All this assumes that you're a typical end user. If your needs are more complex or if this procedure doesn't work for you, you may have to read more about the ntp system. Documentation can be found (among other places) at http://www.eecis.udel.edu/~mills/ntp/html/index.html Q. Basically, how does ntpd work? The drift file (it's just a single line) contains information about how your system clock differs from the correct time and the rate at which it gains or loses time. Approximately every hour ntpd, which is continuously active, queries the time servers you've specified and recalculates the correct values for the drift file. In between, it periodically nudges your system clock in the right direction to compensate for its error, avoiding any abrupt changes. The nudging is determined by the latest data in the drift file. If the drift file is missing, ntpd recreates it by querying the time servers over a period of several minutes and noting how much drift has taken place between queries. The algorithms for that operation are quite sophisticated. --------------- I'd welcome any corrections or improvements to this description, which I hope will be useful. Paul