Leap seconds and the world of Tru64

Hello gurus,

Currently, I have a mix of servers and workstations - XP1000s, AS4100s,
ES40s - running Tru64 4.0F and 5.1B, and getting their time source from an
NTP server.  A question was raised by one of the engineers regarding what
happens to the OS and the system when a leap second occurs?  Does the
system repeat a second or 'freeze' for a second?  I've poked around on the
web and haven't found anything of much use.

Thanks for your help!
Chad