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Re: question about net address

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On Sun, Mar 19, 2023 at 06:38:41PM +0800, coreyh@free.fr wrote:

[...]

> * 188.66.63.1/24 is a range, not a single host in SPF
> * why it's not written as 188.66.63.0/24 which is more clear?

My hunch is that they are meant to be equivalent, as, for
example 192.168.63.42/24, or actually any 192.168.63.x for
x in [0..255].

The problem with this notation is that its semantics are
context dependent: it can denote a host address cum network
mask (as in a CIDR interface spec) or a CIDR network range.

The "context" is provided by the application trying to grok
the notation, so it will vary :-)

The canonical way to express the network part would be to
set the host part to zero, which in this case would be,
as you stated, 192.168.63.0/24. This goes along nicely with
the convention [1] that the bottom address in CIDR is
reserved for the network address, and the top for the
broadcast address. But the non-canonical ways can be seen
just as equivalent -- or erroneous. The software seems to
prefer the former, and silently masks out the network part
(I'd do that, too).

Cheers

[1] AFAIK this is just a convention. I think you can have
   IPv4 subnets where the bottom and the top addresses are
   actual host addresses; this is particularly useful when
   the subnet has just two addresses (i.e. /31), for
   example in a "transfer net".

-- 
t

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question about net address coreyh@free.fr - 2023-03-18 12:30 +0100
  Re: question about net address Markus Schönhaber <debian-user@list-post.mks-mail.de> - 2023-03-18 13:40 +0100
  Re: question about net address Timothy M Butterworth <timothy.m.butterworth@gmail.com> - 2023-03-18 14:30 +0100
  Re: question about net address Kushal Kumaran <kushal@locationd.net> - 2023-03-18 23:20 +0100
    Re: question about net address coreyh@free.fr - 2023-03-19 00:40 +0100
      Re: question about net address David Christensen <dpchrist@holgerdanske.com> - 2023-03-19 11:10 +0100
        Re: question about net address coreyh@free.fr - 2023-03-19 11:30 +0100
          Re: question about net address Joe <joe@jretrading.com> - 2023-03-19 11:40 +0100
          Re: question about net address Jeremy Ardley <jeremy@ardley.org> - 2023-03-19 11:40 +0100
            Re: question about net address coreyh@free.fr - 2023-03-19 11:40 +0100
              Re: question about net address jeremy ardley <jeremy@ardley.org> - 2023-03-19 11:50 +0100
              Re: question about net address <tomas@tuxteam.de> - 2023-03-19 12:10 +0100
              Re: question about net address Greg Wooledge <greg@wooledge.org> - 2023-03-19 13:20 +0100
                Re: question about net address Curt <curty@free.fr> - 2023-03-19 18:20 +0100
                Re: question about net address David Wright <deblis@lionunicorn.co.uk> - 2023-03-19 19:50 +0100
              Re: question about net address Stefan Monnier <monnier@iro.umontreal.ca> - 2023-03-19 16:00 +0100
            Re: question about net address Yassine Chaouche <a.chaouche@algerian-radio.dz> - 2023-03-19 12:10 +0100
              Re: question about net address <tomas@tuxteam.de> - 2023-03-19 12:20 +0100
              Re: question about net address <tomas@tuxteam.de> - 2023-03-19 12:20 +0100
                Re: question about net address Nicolas George <george@nsup.org> - 2023-03-19 12:20 +0100
                Re: question about net address Jeremy Ardley <jeremy@ardley.org> - 2023-03-19 12:40 +0100
                Re: question about net address Nicolas George <george@nsup.org> - 2023-03-19 12:50 +0100
                Re: question about net address Greg Wooledge <greg@wooledge.org> - 2023-03-19 13:30 +0100
                Re: question about net address David Wright <deblis@lionunicorn.co.uk> - 2023-03-19 18:30 +0100
                Re: question about net address David Wright <deblis@lionunicorn.co.uk> - 2023-03-19 19:50 +0100
                Re: question about net address Jeremy Ardley <jeremy@ardley.org> - 2023-03-20 00:40 +0100
                Re: question about net address fh@dnsbed.com - 2023-03-20 01:30 +0100
                Re: question about net address Stefan Monnier <monnier@iro.umontreal.ca> - 2023-03-21 23:30 +0100
                Re: question about net address Jeremy Ardley <jeremy@ardley.org> - 2023-03-22 00:00 +0100
                Re: question about net address David Wright <deblis@lionunicorn.co.uk> - 2023-03-22 00:50 +0100
                Re: question about net address David Wright <deblis@lionunicorn.co.uk> - 2023-03-22 15:50 +0100
                Re: question about net address Jeremy Ardley <jeremy@ardley.org> - 2023-03-19 12:40 +0100
                Re: question about net address Yassine Chaouche <a.chaouche@algerian-radio.dz> - 2023-03-19 13:10 +0100
                Re: question about net address Curt <curty@free.fr> - 2023-03-19 18:10 +0100
              Re: question about net address fh@dnsbed.com - 2023-03-19 12:40 +0100
                Re: question about net address <tomas@tuxteam.de> - 2023-03-19 13:00 +0100
              Re: artifiial intelligence (was: Re: question about net address) Yassine Chaouche <a.chaouche@algerian-radio.dz> - 2023-03-20 10:30 +0100
          Re: question about net address David Christensen <dpchrist@holgerdanske.com> - 2023-03-19 23:20 +0100
  Re: question about net address Yassine Chaouche <a.chaouche@algerian-radio.dz> - 2023-03-19 10:00 +0100
    Re: question about net address Yassine Chaouche <a.chaouche@algerian-radio.dz> - 2023-03-19 10:10 +0100
    Re: question about net address debian-user@howorth.org.uk - 2023-03-19 17:50 +0100

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