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Date: Thu, 15 Feb 1996 15:37:53 -0500
From: "Garrett A. Wollman" <wollman@lcs.mit.edu>
Message-Id: <9602152037.AA13188@halloran-eldar.lcs.mit.edu>
To: Nate Williams <nate@sri.MT.net>
Cc: hackers@FreeBSD.org, wollman@FreeBSD.org
Subject: Broadcast, Netmask, and other such information
In-Reply-To: <199602152029.NAA01202@rocky.sri.MT.net>
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<<On Thu, 15 Feb 1996 13:29:36 -0700, Nate Williams <nate@sri.MT.net> said:

> hosts:                                  hosts:
>  10.5.5.1 - 10.5.5.31                    10.5.5.32 - 10.5.5.63
> netmask:                                netmask:
>  255.255.255.224                         255.255.255.192
> broadcast:                              broadcast:
>  10.5.5.31                               10.5.5.63

10.5.5.31 is not a valid host address.  (Neither is 10.5.5.0, which
you correctly avoided using; it means ``this host''.)

The netmask must be the same for all subnets of the same size.  In
this example, it should be 255.255.255.224.  The network you describe
would then be referred to as 10.5.5.0/227, 10.5.5.32/227, etc.

> But that doesn't sit well with me, especially that the broadcast address
> is the same IP as the last host

As above, that is not a vaild host address.

>, and that the netmask of the last group
> is the same as the entire class C.

> Am I really confused, or can someone else tell me how to calculate
> these?

You are really confused.  Hopefully this will unconfuse you.  Part of
the confusion may result from using classful terms in a classless
world.  It Used To Be Easier.

-GAWollman

--
Garrett A. Wollman   | Shashish is simple, it's discreet, it's brief. ... 
wollman@lcs.mit.edu  | Shashish is the bonding of hearts in spite of distance.
Opinions not those of| It is a bond more powerful than absence.  We like people
MIT, LCS, ANA, or NSA| who like Shashish.  - Claude McKenzie + Florent Vollant