question regarding recommended PTR record configuration with multiple mail sites hosted on same IP

[Gregory Hicks]

> Date: Thu, 09 Feb 2006 02:17:04 -0600
> From: Albert Croft <acroft at cyber-wizard.com>
> To: BIND Users Mailing List <bind-users at isc.org>
> Subject: question regarding recommended PTR record configuration with multiple 
mail sites hosted on same IP
> 
> I appologise if I waste anyone's time-I just wish to be clear on something.
> 
> I often see mentioned that there should be a PTR record set up for a 
> mail server, but what is the recommendation in a case where multiple 
> sites share a mail server? In other words, there exists something like 
> (I can provide actual hostnames/IPs, if needed):
> 
> host.domain00.com. IN A 1.2.3.4
> mail.domain01.com. IN A 1.2.3.4
> mail.domain02.com. IN A 1.2.3.4
> mail.domain03.com. IN A 1.2.3.4
> 
> Should there be a PTR record for each name entry? Or just one, and if 
> so, what should it refer to? I seem to recall seeing mention in an older 
> copy of _DNS_and_Bind_ of some systems not behaving properly when seeing 
> multiple PTR records-is this still the norm?

Pick one name as the 'owner' of the PTR and make a PTR record for that
name.

The problem with multiple names for PTRs is the way that Bind handles
multiple names assigned to one IP address.  It make a "round robin" out
of them.  I get a reply containing all four records.  You would get a
reply containing all four records but the first record that *I* got
becomes the last record that you get.  Your first record bcomes the
last record that someone else gets...  And so on.


> 
> Thank you in advance for your time and consideration.
> 
> -- 
> -Albert Croft
> 
> 

-------------------------------------------------------------------
Gregory Hicks                        | Principal Systems Engineer
Cadence Design Systems               | Direct:   408.576.3609
555 River Oaks Pkwy M/S 6B1          | Fax:      408.894.3400
San Jose, CA 95134                   | Internet: ghicks at cadence.com

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