Denys writes:
> Never use addresses ending in 0, 1 or 255.
>
> .0 is used to describe the entire network.
> .1 is used as the router address between the network and the rest of
>    the Internet
> .255 is the broadcast address.

The .1 thing is just a convention, and obviously you can't "never use"
this address as you obviously have to assign it to the router if you
want to use .1 for this purpose.  Since this is such a common convention,
there is probably a small security advantage in using an unusual address
for your default gateway.

I seem to recall that the original reason why .0 could not be reliably
used is that in the early days some vendors used zero bits to indicate
a broadcast rather than one bits as seems to be universally done today.
Thus some networks used .0 for the broadcast address, and .255 would
have been a perfectly valid individual station address.  People simply
avoided both .0 and .255 so that they didn't have to worry about it.

G.