Failover DNS settings

[NonStop]

Hello guys,

we do have two 3CX instances running on debian (location A with A Public IP, Location B with B public IP). Location A is the main one, B is the passive one. Once its switched to passive one, there is always issue with correct resolving DNS as it takes couple of restarts of passive one, activating license, clearing cache on chrome where web client in running etc. We do have most of the users running on LAN, but also like 20-30% from outside of LAN.

Can you please suggest how to adjust DNS settings to make it working properly??

 

[ChrisC_3CX]

DNS record changes do need some time to take effect due to things like, DNS TTL, DNS propagation time and DNS cache. That said, bear in mind the following:

• A 3CX PRO License has a TTL of 6 hours where a 3CX ENT License has a TTL of 5 minutes.
• We cannot control DNS global propagation but do bear in mind that we use Google DNS so I'd recommend, if possible, having your remote sites use Google's DNS too to help speed this up (Primary: 8.8.8.8 , Secondary: 8.8.4.4)

 

[NonStop]

So basically not even for LAN there is not much we can do? We do have ENT license.

 

[ChrisC_3CX]

So basically not even for LAN there is not much we can do? We do have ENT license.

Just to clarify first:

When you say LAN, are you referring to users on the same LAN as PBX A? If yes, do bear in mind that this is considered an unsupported scenario for the 3CX Failover as it would be considered a Local-to-Cloud Failover configuration. We only support Local-to-Local or Cloud-to-Cloud: https://www.3cx.com/docs/failover/#h.9pyv4ra4v56x

Is this the setup you're using? Also, what are the LAN users using, is it 3CX Windows Apps, 3CX Webclients, IP Phones, etc?

 

[NonStop]

Both PBX are on the same LAN clients, but using public records (FQDN) as we have remote workers. All users are using webclients, some of them mobile app

 

[ChrisC_3CX]

Both PBX are on the same LAN clients, but using public records (FQDN) as we have remote workers. All users are using webclients, some of them mobile app

If both PBX are on the same LAN and therefore share the same Public IP then DNS is completely out of the picture, at least for the remote users.

I feel we need to clear this up a bit so please provide the following information:

• Are both PBXs behind the same public IP?

• Are both PBX's behind the same firewall?

• Are you using the FQDN for registration and provisioning on the local endpoints?

• Do you happen to have a local DNS?