25 Jun
1996
25 Jun
'96
6:37 p.m.
The usage is actually 75%, as there are effectively three addresses: the two ends (00 and 01) and the broadcast address for the network (11). 10 is the unused address.
You don't waste a broadcast address on a, let's say, /24 network but you have to consider it as waste if you plan to use *a lot* of /30 networks. Still, most of the routing protocols use broadcasting so I guess that's what you meant when you said it wasn't a waste... - Hugh