Q: Can a zone be an NTP client or server?
A1: A zone
can be an NTP server.
A2: The NTP client software sets the system
time clock shared by all zones, including the global zone. By default,
non-global zones cannot do this. However, the global zone administrator
can give a zone the ability to change the system time clock with the
"sys_time" privilege. Be aware that this changes the time clock for all
zones.
See http://blogs.sun.com/JeffV/entry/shrink_wrap_security1 for an example. (February 2009)