[Operators] about srv record

Josemar Müller Lohn lohn at lohn.us
Tue Aug 16 12:22:42 UTC 2011


But, anyway, if you ask for a SRV record to your DNS, it will only search
for a SRV entry in the internal table and answers it.
If you ask for an A record, it will search for an A record and then search
for a CNAME record to answer.
To this works there must be a SRV-CNAME like record.
For those who administers databases understand more clearly, the primary key
for the rows in the DNS database is formed by the canonical name AND the
register type.
So, AFAIK, there is no way to delegate a SRV record using CNAME.

Greetings,
 <http://lo.hn/> Josemar Müller Lohn

Cel: (48) 9137-0717
j at lo.hn
http://lo.hn




On Tue, Aug 16, 2011 at 06:40, Dave Cridland <dave at cridland.net> wrote:

> On Tue Aug 16 09:47:35 2011, Kevin Smith wrote:
>
>> On Mon, Aug 15, 2011 at 8:44 AM, Dave Cridland <dave at cridland.net> wrote:
>> > On Sat Aug 13 23:34:56 2011, Josemar Müller Lohn wrote:
>> >>> Is it valid to so:
>> >>> _xmpp-client._tcp.alice.com. CNAME _xmpp-client.bob.com.
>> >>
>> >> You can only get a CNAME answer when you ask for an A record.
>> >
>> > I don't think that's true.
>> >
>> > I think it may well choke the resolvers in many XMPP implementations,
>> mind,
>> > but I think it ought to work according to the specifications. A CNAME
>> merely
>> > states to restart the resolution using the new name.
>> >
>> > Specifically, the requirement that a name with a CNAME record MUST NOT
>> have
>> > any other records (aside from certain DNSSEC ones) would appear to
>> support
>> > that.
>>
>> Is this true? My understanding was that the target for an SRV record
>> explicitly could not be a CNAME, and that the lookup done by XMPP was
>> explicitly SRV. (That is: I don't believe it's valid)
>>
>
> The RHS of a SRV cannot have a CNAME record, but I think a SRV lookup can
> legitimately return a CNAME.
>
> So:
>
> _xmpp-client._tcp.alice.com. CNAME _xmpp-client._tcp.bob.com.
> _xmpp-client._tcp.bob.com. SRV 1 0 5222 xmpp.bob.com.
>
> Is legal, whereas:
>
> _xmpp-client._tcp.alice.com. SRV 1 0 522 xmpp.alice.com.
> xmpp.alice.com. CNAME xmpp.bob.com.
>
> Is not.
>
>
> Dave.
> --
> Dave Cridland - mailto:dave at cridland.net - xmpp:dwd at dave.cridland.net
>  - acap://acap.dave.cridland.net/**byowner/user/dwd/bookmarks/<http://acap.dave.cridland.net/byowner/user/dwd/bookmarks/>
>  - http://dave.cridland.net/
> Infotrope Polymer - ACAP, IMAP, ESMTP, and Lemonade
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.jabber.org/pipermail/operators/attachments/20110816/731b31a7/attachment.htm>


More information about the Operators mailing list