Re: [Exim] Inbound Hosts without valid rDNS

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著者: Exim User's Mailing List
日付:  
To: Jeff Lasman
CC: Exim User's Mailing List
題目: Re: [Exim] Inbound Hosts without valid rDNS
[ On Tuesday, December 30, 2003 at 10:08:44 (-0800), Jeff Lasman wrote: ]
> Subject: Re: [Exim] Inbound Hosts without valid rDNS
>
> > > I am not
> > > saying that the hostname of the server has to be this same DNS
> > > name. I'm only saying:
> > > 1.2.3.4 -> blah.dom
> > > blah.dom -> 1.2.3.4
> > >
> > > and the mail server could be using mail.someotherdomain.lan with ip
> > > 1.2.3.4
>
> This is NOT broken reverse DNS.


Yes, actually, it is.

> It's reverse DNS pointing to the system
> while forward DNS is set for a domain name hosted on the system.


Which is "broken reverse DNS", almost by definition.

(though of course it's not the only way to "break" reverse DNS)

> And it's about all you can do if you've got multiple domains hosted on
> the same IP#.


Sorry, that's also completely and totally false on all fronts.

1. sane administrators don't use IP#s to host either multiple e-mail or
HTTP domains, and there's little, if any, real need to "host"
multiple domains for any other common protocol (e.g. DNS, FTP, etc.).
(SSL is about the only protocol that needs a unique IP per server,
and even the requirement for it will eventually disappear)

2. you can, as has been repeated zillions of times now, easily have
multiple hostnames for the same address and still have valid,
correct, and complete reverse DNS for that address.

--
                        Greg A. Woods


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