RE: [Exim] Inbound Hosts without valid rDNS

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Autor: Eli
Fecha:  
A: 'Kjetil Torgrim Homme', 'Exim User's Mailing List'
Asunto: RE: [Exim] Inbound Hosts without valid rDNS
> I believe I understand DNS, thank you.

No, no you don't - none of us do... at least not nearly as well as Greg does
- he was right there helping when Bob Dole invented the Internet :(

> but _every_ Unix host has such a primary hostname, it's the one you get
> when you call gethostname(2) or uname(2). similarily, Windows machines
> have _one_ primary name associated with them.


But what if I name my machine 1.0.0.10.in-addr.arpa, and that's a PTR to
multiple host names!! What then!!


Actually, Greg can be stuffing his socks down his own mouth right about now:

[root@server!~] dig +nocomments www.planix.com

; <<>> DiG 9.2.1 <<>> +nocomments www.planix.com
;; global options:  printcmd
;www.planix.com.                        IN      A
www.planix.com.         14024   IN      A       204.29.161.33
planix.com.             14119   IN      NS      ns.weird.com.
planix.com.             14119   IN      NS      ns.wrede.org.
planix.com.             14119   IN      NS      ns.planix.com.
;; Query time: 4 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Wed Dec 31 22:50:22 2003
;; MSG SIZE  rcvd: 114


[root@server!~] dig +nocomments -x 204.29.161.33

; <<>> DiG 9.2.1 <<>> +nocomments -x 204.29.161.33
;; global options:  printcmd
;33.161.29.204.in-addr.arpa.    IN      PTR
33.161.29.204.in-addr.arpa. 14133 IN    PTR     whome.planix.com.
161.29.204.in-addr.arpa. 14133  IN      NS      ns.wrede.org.
161.29.204.in-addr.arpa. 14133  IN      NS      ns.planix.com.
;; Query time: 4 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Wed Dec 31 22:50:36 2003
;; MSG SIZE  rcvd: 117


[root@server!~]


Well I'll be darned! Seems Greg hasn't set up proper reverse DNS for his
own little consulting company! What to do!?

-----Original Message-----
From: exim-users-admin@??? [mailto:exim-users-admin@exim.org] On Behalf
Of Kjetil Torgrim Homme
Sent: Wednesday, December 31, 2003 9:29 PM
To: Exim User's Mailing List
Subject: Re: [Exim] Inbound Hosts without valid rDNS

On Wed, 2003-12-31 at 22:47, Greg A. Woods wrote:
> [ On Wednesday, December 31, 2003 at 16:23:58 (+0100), Kjetil Torgrim

Homme wrote: ]
> > Subject: Re: [Exim] Inbound Hosts without valid rDNS
> >
> > note it says "for every IP address", not "for every A record".
>
> If you had bothered to try and understand the reverse DNS and how the
> DNS as a whole is designed then it would be abundantly clear to you
> that what you've quoted is incomplete, and what you say above is
> extremely misleading.


I believe I understand DNS, thank you.

> There is _no_such_thing_ as an "official" or "primary" hostname in the
> DNS, nor can there ever be any such construct, _by_its_very_design_.


but _every_ Unix host has such a primary hostname, it's the one you get
when you call gethostname(2) or uname(2). similarily, Windows machines
have _one_ primary name associated with them.

> > trying to get that changed will be almost impossible.
>
> You wouldn't know unless you've tried it as I have many times, in which
> case you'd have found out that it's not that difficult at all in the
> vast majority of cases and then you wouldn't have said what you said.


there are more worthy windmills to tilt at. as deployed, current best
practice is to have one PTR to the primary name of the host. I can't
see any advantages to changing this policy.
--
happy new year!
Kjetil T.


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