setting up DNS

[Alex728]

in another thread, the issue was raised of how with some configs, all the local SIP phones will deregister if your WAN (broadband) circuit is not working, as asterisk tries to register the SIP trunks and doesn't get the DNS results...

One workaround was to set up DNS server on the Asterisk machine which is apparently what TB pro does.

Any tips on how to do this with PiAF? would be handy "just in case" broadband drops when I am not in the office (to disable the sip trunks) so the rest of the phone system doesn't stop working..

 

[rugby]

webmin will make this easier for you to set up. I have a router that does my DHCP and also handles internal DNS so my lookups for local servers works no matter if my internet goes down.

 

[mac]

Would this be necessary if you already have windows domain dns servers in lan?

 

[Alex728]

this is the thing

I don't have a windows domain server in this LAN.

The phones and the PiaF box don't even have domain "names", they are all set up on static internal IP addresses.

My router does do DHCP and some name resolution, (it is currently shown as DNS client and otherwise works) but what happens is if the broadband is disconected, Asterisk gets confused as its trying to resolve the IP addresses of the SIP trunks - on not finding these it then deregisters all the SIP devices.

To stop this, I have to manually access freepbx and click "disable trunk" in SIP trunks. But I work flexible hours and are not always in this office. When I move to production, this failure mode will be an annoyance to end-users as the "normal" phones will stop working as well as the SIP trunks!

This known issue is what I am trying to get round.

 

[rugby]

You can set up an internal DNS using a cheap linux box. Set up the domain as a .lan suffix such as companyname.lan and then have the static IP addresses resolve to names that way. Such as:

pbx.companyname.lan

Then, once you set that up, you can point the PIAF box to that DNS server as it's primary server, and any phones can point to it as well.

 

[Alex728]

I found a reference to BIND in webmin but any pointers on how to set PiAF to work in the same way as trixbox (pro) is purported to do?

As I mentioned elsewhere I am a relative newbie to Linux, so wouldn't have expected DNS to affect devices specified with just dotted IP addresses, but clearly it does.

if the broadband is up , then I want the SIP trunks DNS lookup to resolve to whatever the SIP servers are.

if for whatever reason the broadband circuit is not working, I want the DNS to provide the correct IP addresses for all the local phones, but for Asterisk dnsmgr to receive whatever result is needed so the internal phones all work, the Zap channels work, but if someone tries to call out on the SIP trunks they get a NU tone (reorder) rather than the entire system collapsing until I have to manually access the system and disable the sip trunks.

Knowing murphys law something like this may happen when I am not in the office! Its just from a end users POV (especially those used to a separation of voice and data) they don't expect their local phone extension to go down if the "Internet is broken"....

in the meantime i did at least make a document for the users explaining this issue and how I have to change the settings manually resolve it, illustrated by this (might be familiar to those who enjoy British comedy)