[SR-Users] Avoid resolving names by DNS

[Daniel-Constantin Mierla]

On 9/1/10 7:01 PM, Andrei Pelinescu-Onciul wrote:
> On Sep 01, 2010 at 18:49, Klaus Darilion<klaus.mailinglists at pernau.at>  wrote:
>> kamailio>= 3.0 is based on ser's core which has implemented its own
>> caching resolver library. I do not know if there is a way to disable
>> it complete and use the system's stub resolver. You could try the
>> "use_dns_cache" option:
>> http://sip-router.org/wiki/cookbooks/core-cookbook/devel#dns_parameters
> Yes, if you disable the dns cache it will use the system resolver.

when the cache is enabled and the record is not cached, will first dns 
query find the records in /etc/hosts and then cache it? Or in other 
words, if a query to internal cache fails, then is used the system resolver?

Just for sake of completing info in this thread, disabling completely 
the internal cache is by global parameter:
dns_cache_init=no

Thanks,
Daniel

> It's also used during the initial startup phase, when the dns cache is
> not yet fully initialized.
>
> You could also leave the cache enabled and add/remove records by hand
> (using sercmd or xmlrpc) using the dns rpcs (e.g. dns_add_a,
> dns.add_srv, dns.delete_a a.s.o, for more info see
> http://sip-router.org/docbook/sip-router/branch/master/rpc_list/rpc_list.html#dns.add_a
> ).
>
> Andrei
>
>> regards
>> klaus
>>
>> Am 01.09.2010 17:10, schrieb Santiago Soares:
>>> Hello,
>>>
>>> I'm using kamailio as a simple load balancer.
>>> My dispatcher list is something like that:
>>>
>>> 1   sip:server1:5060
>>> 1   sip:server2:5060
>>> 2   sip:server1:5060
>>>
>>> and /etc/hosts is
>>>
>>> 10.1.1.1   server1
>>> 10.1.1.2   server2
>>>
>>> When I want to do some maintenance task in one of the servers, server2,
>>> for exemple, I simply change /etc/hosts like that:
>>>
>>> 10.1.1.1   server1
>>> 10.1.1.1   server2
>>>
>>> And all the traffic is redirected to server 1. It's a simple yet
>>> effective way to remove a server from balancing.
>>> The thing is that it works on kamailio 1.5.3, but on kamailio 3.0.3 it
>>> doesn't work, since kamailio appears to resolv names only by DNS.
>>> I receive this message on startup:
>>>
>>> Sep  1 12:04:32 install /usr/local/sbin/kamailio[16077]: ERROR:
>>> dispatcher [dispatch.c:241]: could not resolve server1
>>> Sep  1 12:04:32 install /usr/local/sbin/kamailio[16077]: ERROR:
>>> dispatcher [dispatcher.c:247]: no dispatching list loaded from file
>>> Sep  1 12:04:32 install /usr/local/sbin/kamailio[16077]: ERROR:<core>
>>> [sr_module.c:874]: init_mod(): Error while initializing module dispatcher
>>>
>>>
>>> Is there any way to avoid this behavior, and force kamailio to use
>>> /etc/hosts?
>>>
>>> Thank you.
>>>
>>> Santiago Soares
>>> Fone: (41) 8488-0537
>>>
>>>
>>>
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-- 
Daniel-Constantin Mierla
http://www.asipto.com/