underscore in A or PTR records

[Sten Carlsen]

> On 17 Feb 2021, at 12.34, ONRUBIA AVILES Carlos (CCS/MST) <carlos.onrubia.aviles at proximus.com> wrote:
> 
> Hello,
> 
> Indeed my question was on A record but the issue is on PTR record.
> I can configure the following line:
> 
> _ptr.dekil.nl.      3600    IN      PTR     _81.99-129-109.adsl-dyn.isp.dekil.nl
> 
> It works....we can use "_"  in both sides.
> 
> 
> But what is strange is that the following configuration do not work:
> 
> 9.10.238.195.in-addr.arpa.       3600    IN      PTR     por_tal-bis.skynet.be.
> 
> "_" is not allowed
> 
> Is it due to extra check by bind when it sees it is an arpa zone so no  "_" is allowed?

As previously mentioned, the RFCs expressly forbids the "_" in names.

I assume that a leading "_" slips past Bind's control because it "could" be part of a valid but at compile time unknown _tcp -like label.

> 
> 
> Regards,
> 
> Carlos,
> 
> 
> Sensitivity: Internal Use Only
> 
> -----Original Message-----
> From: Ondřej Surý <ondrej at isc.org>
> Sent: 17 February 2021 10:52
> To: ONRUBIA AVILES Carlos (CCS/MST) <carlos.onrubia.aviles at proximus.com>
> Cc: Mark Andrews <marka at isc.org>; bind-users at lists.isc.org
> Subject: Re: underscore in A or PTR records
> 
>> 
>> On 17. 2. 2021, at 9:50, ONRUBIA AVILES Carlos (CCS/MST) <carlos.onrubia.aviles at proximus.com> wrote:
>> 
>> The issue we face is that a telecom provider ask us to implement a PTR record with a name like “example_try.net"
> 
> You are mixing the two things here. If the provider has asked you to create a PTR record, why do you keep trying to create a forward record? There’s some information missing somewhere.
> 
> Ondrej
> --
> Ondřej Surý (He/Him)
> ondrej at isc.org
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