[SR-Users] Understanding DNS resolution done by Kamailio

[Daniel-Constantin Mierla]

Hello,


On 04/08/14 14:20, Igor Potjevlesch wrote:
>
> Hello Daniel,
>
> Thank you. If I use the resolver included in Kamailio and if the 
> response from the resolver is negative, is there a new DNS request 
> sent for outgoing uri resolution?
>

it should not be any other dns request -- it will fail sending.

Cheers,
Daniel

> If not, that would mitigate the volume of DNS requests sent.
>
> Regards,
>
> Igor.
>
> *De :*sr-users-bounces at lists.sip-router.org 
> [mailto:sr-users-bounces at lists.sip-router.org] *De la part de* 
> Daniel-Constantin Mierla
> *Envoyé :* vendredi 1 août 2014 08:46
> *À :* Kamailio (SER) - Users Mailing List
> *Objet :* Re: [SR-Users] Understanding DNS resolution done by Kamailio
>
> Hello,
>
> I don't think there is a way to disable dns for outgoing uri 
> resolving, if you want disabling all dns.
>
> The dns timeout is can be configured at the operating system level.
>
> To avoid the sip worker blocking, you can try:
>
> a) look at $nh(d) and if it is not an IP, then you can use 
> async_route() (async_task_route() would be better, but now only in 
> devel) or mqueue+rtimer to pass the relaying of the request to another 
> worker process
>
> b) and an intermediary proxy, so you send the requests with FQDN to it 
> and it will return back to the proxy. You can send the dst-uri via 
> some custom headers. This would be like:
>
> [ua1] <===> [kamailio main] <===> [kamailio dns] <===> [kamailio main] 
> <===> [ua2]
>
> kamailio dns should not do record routing, because requests within 
> dialog should have IP addresses.
>
> Cheers,
> Daniel
>
> On 29/07/14 14:31, Igor Potjevlesch wrote:
>
>     Hello,
>
>     I’m using Kamailio 4.1 and I’m wondering how to avoid external DNS
>     resolution.
>
>     I have the following config:
>
>     dns_cache_init=no
>
>     use_dns_cache=no
>
>     dns=no
>
>     rev_dns=no
>
>     Even with this config, I have many and many DNS query on SRV _sip
>     for the hostnames set in carrierroute module.
>
>     These requests are not useful because the A resolution is done by
>     /etc/hosts.
>
>     Major problem with this, is that when I have a DNS issue or IP
>     transit issue, Kamailio waits for resolution timeout and becomes
>     overloaded. As a consequence, Kamailio can’t treat others SIP
>     requests like REGISTER because he stuck in DNS resolution.
>
>     Regards,
>
>     Igor.
>
>
>
>
>     _______________________________________________
>
>     SIP Express Router (SER) and Kamailio (OpenSER) - sr-users mailing list
>
>     sr-users at lists.sip-router.org  <mailto:sr-users at lists.sip-router.org>
>
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>
>
>
> -- 
> Daniel-Constantin Mierla -http://www.asipto.com
> http://twitter.com/#!/miconda  <http://twitter.com/#%21/miconda>  -http://www.linkedin.com/in/miconda

-- 
Daniel-Constantin Mierla - http://www.asipto.com
http://twitter.com/#!/miconda - http://www.linkedin.com/in/miconda

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