Subject: Re: [Enum] Backward compatibility

From: Brandner Rudolf <[email-masked]>
Date: Wed, 13 Feb 2002 11:12:08 +0100

This is very good. Thank you very much for that information and clarification. 

Rudi

> -----Ursprüngliche Nachricht-----
> Von: Patrik Fältström [mailto:[email-masked]]
> Gesendet: Mittwoch, 13. Februar 2002 09:01
> An: Brandner Rudolf; [email-masked]
> Betreff: Re: [Enum] Backward compatibility
> 
> 
> --On 2002-02-12 17.40 +0100 Brandner Rudolf
> <[email-masked]> wrote:
> 
> > let's assume that an end system (or terminal) sends out a 
> DNS request
> > with a NAPTR in it and this request hits an intermediate node still
> > running an old version of BIND (i.e. BIND 5).
> > 
> > What will happen with that request?
> 
> Executive summary:
> 
> There will not be any problem.
> 
> 
> Detailed summary:
> 
> You have two different issues here, and then another one hidden in the
> details:
> 
> (a) Can an old version of for example BIND be primary/master 
> server for
> NAPTR resource records?
> 
> - A DNS server software can only be primary/master for resource record
> types which one can enter into the software. I.e. it have to do with
> managment and administration.
> 
> (b) If you have a non-primary server, can it be a forwarding 
> / caching only
> server for resource record types it does not understand?
> 
> - Yes, a DNS program do according can handle DNS packets 
> where the resource
> record type is unknown.
> 
> 
> And now the hidden one:
> 
> (c) Can Bind (explicitly) before version 8 be secondary 
> server for a zone
> which have unknown RR types?
> 
> - No, because the secondary server caches the zone info on 
> disk, and it can
> then not parse the output when it tries to read it after a reboot.
> 
> 
> Note 1: NAPTR was introduced for some time ago, so I even think some
> version 4 of Bind do handle NAPTR.
> 
> Note 2: If you run a DNS software which is older than a year, you have
> other problems, namely security problems, regardless of who 
> has written the
> software.
> 
> Note 3: What is important to know is that the DNS specification itself
> makes it possible to handle unknown RR types.
> 
>        paf
> 

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