Re: endpoint discovery from reverse DNS [Re: other comments on draft-nielsen-v6ops-3GPP-zeroconf-goals-00. txt

[Alain Durand <Alain.Durand@Sun.COM>]

On Nov 5, 2004, at 12:33 PM, Pekka Savola wrote:

> These can certainly be argued many ways, and hopefully these issues 
> can be captured in a revision of palet-tun-auto-disc..
>
> On Fri, 5 Nov 2004, Alain Durand wrote:
> > > As to the attributes of the reverse lookup schemes, one might say a 
> > > few good / bad sides, like:
> > >   - bad side is that requires a lot of records
> >
> >   not an issue as they can be generated with script.
>
> Still, doing so either requires that script be invented and 
> (re-)written by every DNS admin, or be distributed with DNS servers.
> The script is probably very trivial, yes, but this is an ease-of-use 
> factor.

This is a bogus argument. Such a script already exist for generating 
the PTR in the reverse zone.
I wrote a very small ad-hoc perl script (10 lines of code!) to do that, 
I can donate it to the community
if need be.

Another way to solve this non-issue is to get $generate to be adapted 
to generate NAPTR as well.

> If we want to make it extremely simple to set up these services this 
> could be a small minus.
>
> > >   - increases the number of required lookups
> >
> > Not necessarily. Think CNAME and additional section.
>
> CNAMEs in reverse tree?  Granted.  Hopefully no DNS servers would 
> break with such unanticipated usage.

No. I should have been more clear...
When you are resolving a name in the forward tree and there is a CNAME, 
you generally do not
have to do a second query to resolve the CNAME. As the server knows you 
are more than likely to
need that data anyway, it puts it in the additional section. Example:
[halibut:~] alain% dig ftp.sun.com a

; <<>> DiG 9.2.2 <<>> ftp.sun.com a
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 11219
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;ftp.sun.com.                   IN      A

;; ANSWER SECTION:
ftp.sun.com.            86400   IN      CNAME   supportfiles.sun.com.
supportfiles.sun.com.   86400   IN      A       192.18.108.101

;; Query time: 87 msec
;; SERVER: 64.81.79.2#53(64.81.79.2)
;; WHEN: Fri Nov  5 13:36:25 2004
;; MSG SIZE  rcvd: 72

	- Alain.