How do I find my local sub-net, to broadcast NTP

[Nathaniel Homier <nathaniel.homier@gmail.com>]

I am trying to get NTP to broadcast the time on my local subnet.  I have 
the ntp.conf uncommented in the proper place.  I put 192.168.1.255 as my 
sub-net but I am not sure.  I have a cable modem>Linksys 4 port 
router>my computer.  My computer's IP address is 192.168.1.100 and my 
router is 192.168.1.1.  Gnome-network-tools shows in devices under the 
broadcast column an IP of 192.168.1.255.  So I assumed that 
192.168.1.255 is the sub-net, or is it 192.168.1.0.

Nate