[asterisk-users] Improving Asterisk's DNS support

[Joseph]

On Wed, 2007-05-02 at 01:34 -0400, Brian Capouch wrote:
> Kristian Kielhofner wrote:
> 
> > 
> >  The intent of my original message was to try to start a discussion
> > on how we can fix a REAL, KNOWN problem with Asterisk to make it
> > better.  I'm not sure what the exact problems are (or even the
> > specific symptoms in all cases), but  I am willing to offer anything
> > that I can (money, testing, etc) to fix this problem.
> > 
> >  I realise you don't know that this is a problem.  However, your tone
> > is *not* what I am looking for in this discussion.
> > 
> 
> For those who haven't ever been bit by this "situation," please believe 
> that it is not only real but devastating.
> 
> Kristian is exactly right: there needs to be an architectural fix that 
> will stop EVERYTHING in the server from hanging when lookups are done 
> (and then hang) for a given IAX/SIP peer.
> 
> I'm not programmer enough to do it, but once it's done I will be 
> eternally grateful.
> 
> Just yesterday I had a situation where our egress circuit was being used 
> temporarily to do a big remote database dump.  As a result, DNS queries 
> to the outside world were taking forever to resolve.  An internal server 
> I have, which talks to a single DNS-named peer in the outside world, 
> hung tight, repeatedly, while the T1 was compromised, even though none 
> of its calls had anything to do with that peer.  It was the core engine 
> that was hung up waiting.
> 
> The worst of it is when there are Zaptel cards in the box, it doesn't 
> even handle call pickups and the like once the DNS hang has begun.
> 
> There are various kludgy workarounds, but at the end of the day it does 
> not seem that the server should hang totally when this situation occurs.
> 
> B.

What a coincidence!
I think this problem is related to a delay I see when asterisk box is
not connected to the Internet. 
When a box running asterisk is not connected to the Internet the
response is very, very slow. 

Example, when no Sip adapters were connected to asterisk it took me over
one minute from the time I typed "reload" to the time I've seen anything
on
the screen.
When, I connected the all the sip adapters and eliminated some entries
in sip.conf and iax.conf, it took only 22-seconds to "reload"

Someone on the asterisk mailing list suggested to check my DNS resolving
system but I don't see any problem with it.
In my resolv.conf:
search inet
nameserver 10.0.0.1

I even entered into firewall DNS all my static IP but it makes no
difference as I'm using IP's with asterisk not "host names"
I've check (run etherape) with system that has Internet connection and
running "reload" asterisk is not trying to contact any external IP.
So I can not figure it out why "reload" in asterisk is so slow without
Internet connection.

-- 
#Joseph