[AusNOG] PTR Records

[Colin Stubbs]

What Mark said.

I'd also note, that while the value returned by the PTR request is
*intended* to be another valid RR (A, AAAA etc)... it can actually be any
ASCII string.

Windows server DNS will convert everything to lowercase and encode some of
the characters however, e.g.

[user at box ~]$ dig @10.4.32.32 PTR 255.32.4.10.in-addr.arpa. +short
my\032isp\032is\032staffed\032by\032muppets.
[user at box ~]$

By the look of it RFC 1035 describes what's expected for DNS resource
records generally, and what PTR is expected to be.

-Colin

On 18 November 2014 11:34, Mark Andrews <marka at isc.org> wrote:

>
> In message <
> CAM9f+Zw4fbWXbr2gne0iLWppywN-oU32Uf4P3H17M1cK3D+JLw at mail.gmail.com>,
> David Beveridge writes:
> >
> > Can anyone point me to any RFC which says that there are restrictions on
> > the name a PTR can point to.
> >
> > I have been told by a certain ISP that I cannot have a PTR pointing to
> > mycompany.com.au as it is NON-standard and which cannot and should not
> be
> > done.  They insist on setting the PTR to mail.mycompany.com.au and
> refuse
> > to do as I ask.
> >
> > I have never heard of any such thing.
> >
> > dave.
>
> There isn't such a restriction.
>
> That said if you are sending email from mail.mycompany.com.au and
> it announces itself as mail.mycompany.com.au in the HELO / EHLO
> then it would be wise for the PTR record to be mail.mycompany.com.au
> and for there to be A/AAAA records for mail.mycompany.com.au.
>
> If your mail server announces itself as mycompany.com.au then the
> PTR record should be set to mycompany.com.au.
>
> Mark
> --
> Mark Andrews, ISC
> 1 Seymour St., Dundas Valley, NSW 2117, Australia
> PHONE: +61 2 9871 4742                 INTERNET: marka at isc.org
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>
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