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Re: [reSIProcate] How does a client build a DNS lookup that restr icts the responses to UDP?


Good deal.  I missed that in the RFC.  On another look at sec. 4.1, I see it
doesn't say to not use NAPTR if the transport is specified but the port is
not.  Rather, I see it just says to use NAPTR if neither the transport or
port are specified.  So, if the transport is specified, it just uses the
default SRV for _sip._udp?  If there's a line that explictly says how this
works regarding the default SRV record, that will help.

Thanks, yall have helped a lot.
Dave


-----Original Message-----
From: Byron Campen [mailto:bcampen@xxxxxxxxxxxx] 
Sent: Thursday, December 07, 2006 1:07 PM
To: Dave Mason
Cc: resiprocate-devel@xxxxxxxxxxxxxxxxxxxx
Subject: Re: [reSIProcate] How does a client build a DNS lookup that restr
icts the responses to UDP?

        This is the behavior specified in RFC 3263, so DNS admins should be
expecting it (although 3263 can be a little tricky to wade through).

Best regards,
Byron Campen

> Hi, I just found a quick followup...
>
> I find that if I do a lookup with a URI such as 
> "sip:user@xxxxxxxxxx;transport=udp", the library ignores the NAPTR 
> records and chooses the _sip._udp.<domain.com> SRV record.  Thus, if 
> the DNS response has a NAPTR with a different preference for UDP such 
> as _sip2._udp.<domain.com>, it will be ignored in favor of the 
> default.
>
> Is this a known condition that DNS admins will take into account, or 
> should I first do a lookup without it, and search those results for 
> UDP transports?
> If none are found, then I do a lookup with ";transport=udp"  
> appended to
> guarantee a UDP response?  (I hate to do two lookups if I don't need 
> to.) What's the proper way to use the library (DnsInterface class) for 
> this case?
>
> Regards,
> Dave
>
>
> -----Original Message-----
> From: Byron Campen [mailto:bcampen@xxxxxxxxxxxx]
> Sent: Tuesday, December 05, 2006 5:04 PM
> To: Dave Mason
> Cc: resiprocate-devel@xxxxxxxxxxxxxxxxxxxx
> Subject: Re: [reSIProcate] How does a client build a DNS lookup that 
> restricts the responses to UDP?
>
>       Well, you can always do sip:user@xxxxxxxxxx;transport=udp. Also, if 
> your stack doesn't support TCP, it should use UDP instead. Lastly, if 
> there are no TCP SRVs in DNS, you should also get UDP results.
>
> Best regards,
> Byron Campen
>
>> Hi,
>>
>> I find that if a DNS server is set up with NAPTR records for a domain 
>> that specify TLS/TCP is most preferred, then TCP, the UDP last, and a 
>> client does a DNS lookup for sip:user@xxxxxxxxxx (through 
>> DnsInterface), the DNS server only returns records for TLS/TCP.
>>
>> How do you configure the lookup on the client side to ask for only 
>> UDP records, even if they are least preferred on the server?
>>
>> Regards,
>> Dave
>> _______________________________________________
>> resiprocate-devel mailing list
>> resiprocate-devel@xxxxxxxxxxxxxxxxxxxx
>> https://list.resiprocate.org/mailman/listinfo/resiprocate-devel
>