Path: utzoo!attcan!uunet!lll-winken!ames!pasteur!ucbvax!DECWRL.DEC.COM!mogul
From: mogul@DECWRL.DEC.COM (Jeffrey Mogul)
Newsgroups: comp.protocols.tcp-ip
Subject: Re: pecial Internet address
Message-ID: <8901260246.AA16760@acetes.pa.dec.com>
Date: 26 Jan 89 02:46:00 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 21

From: mcneill@eplrx7.UUCP (mcneill)

    One machine on our LAN caused a lot of havoc.  It was mistakenly placed on
    the network before it's networks file had been configured correctly.  It
    thought that it's network address was 192.9.200.0.  I seem to remember
    seeing somewhere "never use x.x.x.0 address" (where x ranges from 0 to
    255).  Is my memory correct?  If that is an untouchable address why is it?

I thought we had put this prohibition into RFC950, but on a quick read
I couldn't find it (we did prohibit subnet number 0).

Anyway, I can tell you why you shouldn't do it: because in spite
of the standard for broadcasting (RFC919) which specifies the
use of an ``all-ones'' broadcast address, many hosts (derived
at some point from 4.2BSD) still use the x.x.x.0 address for
broadcasting (if they also understand subnets, that is).

So, using x.x.x.0 or x.x.x.255 is likely to confuse some hosts
and perhaps lead to broadcast storms ... which you don't want.

-Jeff