Can i use DNS or two public IPs?

[Voipuser07]

On perm, Version 16.0.493

Network Settings > Public IP > External IP Configuration

Can I use DNS or two public IPs instead of one? WAN2 takes over when WAN1 fails, but 3CX won't be functional as it has WAN1's static IP.

Thanks in advance.

 

[leejor]

On older versions (pre V 15) you were able to use a DDNS service. No longer. You can set as a dynamic IP, but use a 3CX FQDN.
https://www.3cx.com/community/threads/can-use-noip-com-dns-for-3cx-fqdn.55313/

 

[Voipuser07]

On older versions (pre V 15) you were able to use a DDNS service. No longer. You can set as a dynamic IP, but use a 3CX FQDN.
https://www.3cx.com/community/threads/can-use-noip-com-dns-for-3cx-fqdn.55313/

@leejor
thanks.
I am already using a 3CX FQDN, so simply changing to dynamic IP should work. Can you think of anything not working because of this?

 

[Evolute IT]

@leejor
thanks.
I am already using a 3CX FQDN, so simply changing to dynamic IP should work. Can you think of anything not working because of this?

If you have a Standard or Pro license, the FQDN will take 6 hours to update to the new IP because of DNS TTL.

On Enterprise versions, the delay is 5min to allow faster failover.

So, while the IP has changed and the DNS isn't updated, any remote phones or SBCs won't be able to connect.

 

[craigreilly]

I recently did an ISP change and the IP updated in 10 minutes. I am on a Pro license.

I am not saying that will be the case for everyone - I think the 6 hours is more CYA based on 3cx's experience.

 

[Evolute IT]

I recently did an ISP change and the IP updated in 10 minutes. I am on a Pro license.

I am not saying that will be the case for everyone - I think the 6 hours is more CYA based on 3cx's experience.

It's also depending on what DNS you're using on the other side! ISP DNS are usually slow to update where Google's are blazing fast.

 

[craigreilly]

I haven't used an ISP DNS server in forever... just haven't been reliable.
But I guess, in theory, Googles DNS are an ISP's as well?

 

[Voipuser07]

UPDATE:
it's been 4.5hrs since IP change, can access management console via WAN IP but not via fqdn.

 

[AWS2P]

CYA based

Thanks Craig, learned something

it's been 4.5hrs since IP change, can access management console via WAN IP but not via fqdn.

if you have a windows computer, try to flushdns, doing
execute
cmd
ipconfig /flushdns
then try nslookup FQDN and see if resolve or not