Set the clocks correctly, and schedule the change on all the servers for
a particular time, using (for example) the tinydns timestamp feature
described in http://cr.yp.to/djbdns/tinydns-data.html. When that time
rolls around, all the servers will change their data simultaneously,
My friend Dr. Einstein would like a word with you about your casual
misuse of the word "simultaneously."
Matt Crawford crawdad(_at_)fnal(_dot_)gov Fermilab