[asterisk-users] asterisk fails when DNS or internet fails

[Jeff LaCoursiere]

On Mon, 30 May 2011, Sherwood McGowan wrote:

> True, but with all due respect, if the cache's TTL expires and the OP's 
> PBX cannot reach an external DNS server, they have bigger problems ;-)
> 
> Slainte all!
> The Mick
>

I couldn't disagree more.  In fact I think this problem is more serious 
than it is getting credit for, when asterisk is in use in places where 
Internet connectivity is far from stable.  I have several hotels that have 
gone without Internet connectivity for days, and somewhere between one and 
three days down they can only spottily call within the system, and can't 
make outbound calls on their voice T1.  Its certainly true that they were 
suffering without Internet access, but it is very hard to explain to the 
owners why they can't use their phones.  In fact the symptoms are very 
strange - inbound calls on the T1 get the auto-attendant, but internal 
transfers fail.  No one can call outbound, and only *sometimes* do 
internal extension to extension calls fail.

I still scratch my head about what exactly asterisk is trying to lookup 
that keeps it from being able to place internal SIP calls from extension 
to extension, and sadly the few times this has occurred I wasn't around to 
debug.

Hasn't anyone managed to solve this with something better than a caching 
DNS server, which seems to only last a short while?  What exactly is going 
on that is failing?

Cheers,

j