3cx name servers

[about]

is it just me or is there a problem with the name resolution.

i have 3 pbxs where the domain wont resolve.... all xxx.3cx.co.uk

 

[Saqqara]

What are the dns settings, change to google 8.8.8.8 and recheck

 

[about]

this was using google 8.8.8.8

it seems to be resolving 80% of the time now when i nslookup against 8.8.8.8

problem is our calls werent terminating to the pbx from our number provider when using the domain, but ive changed to IP and it now works also.

 

[FS_Mathieu]

You mean that with IP it's working 100% of time but DNS is ~80% ?

 

[about]

from our provider, terminating the calls to [email protected] meant we recieved no calls at all. I eventually realised that i changet to the IP address and calls worked fine.

I also had some phones not connecting, so had to do a hard entry in the local dns to resolve that.

i perform an nslookup against my name server and it wont resolve it, but then change to google and it also wouldnt resolve..... Since then It now is resolving most the time against google 80%.

this is accross 3 seperate PBXs. i think the other ones are just lucky the dns entry is still cached.

 

[BrenttG]

Could be your provider is intercepting DNS, this is prevalent over in the UK i have heard. The provider will intercept your dns query to whatever dns server, and spoof you a reply from their own dns server allegedly to save bandwidth, but in reality its so they can collect analytics and snoop on what your doing on your connection, some providers here do the same thing not naming any names(comcast). A trick you can do to prove or dis-prove is setup something like openvpn on a remote server somewhere offsite using udp port 53 as its server port, then try to connect to it with the client, it will fail because its being intercepted and spoofed and their dns interception has no idea how to handle openvpn traffic, it just blindly intercepts all port 53 traffic if they are indeed using interception.

I have caught our Cox provider here doing it previously as well, however they had some public backlash and stopped doing it. It makes for some very strange, and tricky problem solving because you would never think to check if your dns replies are being spoofed by a carrier who wants to spy on you, or is assisting a government agency in spying on you....

Think im paranoid and this is all hubub? Think again....
https://labs.ripe.net/Members/babak_farrokhi/is-your-isp-hijacking-your-dns-traffic

 

[about]

i really do think there were issues with DNS on 3cx.co.uk, or just my boxes for some reason.

i say this as it couldnt resolve at my location, one a few clients locatations, on 8.8.8.8 and at my wholesale number provider.

anyway working now, and apparently no-one else has had issues, so no biggy.

 

[cobaltit]

Well you don't need to think there was a DNS issue because clearly it was. But as no one else complained it's likely something localized. 3CX is using Google as authoritative name servers so if you weren't getting answers using 8.8.8.8 then it maybe have been a bad local resolver that they took out or it could be that your configuration is a small minority. Is the provider your using 3CX approved? If not then there might only be a handful of folks using the same configuration you are using.