[asterisk-users] Why asterisk down when inet server down?

[sean darcy]

On 06/18/2010 01:19 PM, Gordon Henderson wrote:
> On Fri, 18 Jun 2010, sean darcy wrote:
>
>> We have a 10.10.0.0 internal network. The asterisk server - 10.10.10.180
>> - has a PRI connection to a T-1. Another server is the router to the
>> internet. All phones in the office and the workstations are on the network.
>>
>> Most of the internal phones are aastra 9133i's. Here the network config
>> from a phone:
>>
>> Network Settings
>>
>>     Basic Network Settings
>>     DHCP                         [ ] Enabled
>>     IP Address                   10.10.10.44_________
>>     Subnet Mask                  255.255.255.0_______
>>     Gateway                      10.10.10.180________
>>     Primary DNS                  10.10.10.180________
>>     Secondary DNS                0.0.0.0_____________
>>
>> If the network server is down, the phones go out of service. From a
>> workstation I can still ssh into the asterisk server. But for some
>> reason the phones don't work. I can console dial out from the server.
>> The asterisk server doesn't need the internet for connectivity.
>>
>> Why do the internal phones go down?
>
> If you mean that the phones simply can't dial and don't actually
> un-register themselves, it probably because asterisk needs a working DNS
> server somewhere, and with no Internet, then your DNS server - which looks
> like your gateway - which I'm guessing is just a dumb forwarder - is
> failling.
>
> I've never undersood quite why asterisk wants to do a DNS lookup for every
> call, but not been bothered enough to do something about it other than to
> run a cacheing DNS server on the asterisk box itself just for it's own
> use.
>
> Gordon
>

I don't know if the phones unregister themselves. They simply show "No 
service"

and sip show peers:

44/44                    (Unspecified)    D   N   A  5060     UNKNOWN

I do run a caching/nameserver on the asterisk box.

I didn't realize asterisk did a DNS lookup for every call, even one 
going out over PRI/DAHDI. That makes no sense, IMHO. It means that you 
couldn't use asterisk as a straight PBX for a T1 (or POTS).

Is there any way of turning off the DNS lookup? Or at least not having 
it become a major failure event?

sean