Thanks Vijay!
Regarding one tiny technical detail.. My understanding from the DNS spec was that a
DNS query may refer to several types in parallel, i.e. to save the need to access the
DNS server multiple times.
is that your understanding as well?
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[EMAIL PROTECTED],
Tel: (847) 632 4616; Fax: (847) 632 3963;
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> -----Original Message-----
> From: Vijay Gurbani [mailto:[EMAIL PROTECTED]]
> Sent: Wednesday, January 31, 2001 9:49 AM
> To: Baniel Uri-CUB001
> Cc: SIP Implementors; Dyer William-QA1394; Miller Trent-QA1400
> Subject: Re: [SIP] Decoding the SIP URL
>
>
> Baniel Uri-CUB001 wrote:
> >
> > So I guess my question is either just too dumb or too boring :(
> > Still, is there any good soul on the list, who has a moment
> to go over the
> > question and respond.
>
> Uri:
>
> I'll take a a shot at it (I have also moved this to the SIP
> Implementors
> list)...
>
> > Say a UAC gets the following SIP URL from its user in the 'To' and
> > 'request URI' fields: "[EMAIL PROTECTED]". How does the
> UAC 'guess' if
> > 'ieee.org' refer to a specific host or a domain? Looks
> like according
> > Bis02 para 1.4.2, the UAC tries to get DNS SRV record
> first, and then A
> > record if the former query has failed. Is that true? If
> yes, looks like
> > according the DNS RFC, one may issue a DNS query w/
> multiple types (e.g.
> > _sip, a, aaaa) and act based on the response. Was that the
> intention of
> > Bis?
>
> That's my understanding. First extract the host portion from
> the R-URI and
> if it is not an IP address, prepend _sip._udp.ieee.org. If the query
> succeeds, you've got your SIP server. If not, try _sip._tcp.ieee.org
> (assuming the UAC supports TCP). If SRV query fails, try
> prepending "sip"
> to the host (sip.ieee.org). If all else fails, try A and
> AAAA RRs. If even
> that fails, then curse and give up (the cursing part is
> optional, though
> very therapeutic :-)).
>
> - vijay
> --
> Vijay K. Gurbani vkg@{lucent.com,research.bell-labs.com,acm.org}
> Internet Software and eServices Group
> Lucent Technologies/Bell Labs Innovations 263 Shuman Blvd., Rm 1A-413
> Naperville, Illinois 60566 Voice: +1 630 224 0216 Fax:
> +1 630 713 0184
>
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