Of course, it's
unattainable. However, keeping
zero downtime as a goal means very sensible
network administration. It means keeping around
spare parts when possible--even the best
support contracts only guarantee
2 hour response time. It means not doing
testing on
production systems. It means not installing
service packs until
the rest of the Net has tested them for you. It means not making
overly complex configurations that are difficult to
troubleshoot when something does go wrong (and go wrong it will.) It means
documenting and
auditing the network so you know when it's going to get
blown out.
Overall, using zero downtime as your goal means you only make changes when necessary, you don't do anything stupid, and you're less likely to have your back against the wall or be caught with your pants down.