DNS Resolution Issue for a DynDNS FQDN on Hosted 3CX Server (V20)

[Ralib]

Hello,

I am experiencing a DNS resolution issue with my hosted 3CX server (V20). I use a DynDNS FQDN to point to my public IP, which updates every 60 seconds when my IP changes.

Issue:

After a public IP change, my DynDNS FQDN updates correctly and resolves to the correct IP on other devices (nslookup, dig return the correct IP).

However, my 3CX server continues resolving the old IP for days preventing external connections from working immediately after the IP change.

It seems that 3CX’s DNS cache does not refresh properly.


Tests Performed:

Verified that DynDNS updates correctly.
Checked DNS resolution from another device (returns the correct IP).
Restarted all 3CX services from the management console (issue resolved).


Questions:

1. Is there a way to manually flush the DNS cache on a hosted 3CX server?


2. Does 3CX apply an extremely high TTL for cached DNS resolutions? If so, can this be adjusted?


3. Can an alternative DNS server be configured to improve DynDNS update handling (e.g., Google DNS 8.8.8.8, Cloudflare 1.1.1.1)?



Thank you in advance for your help!

Best regards,
Ralib from Mauritius island

 

[jed]

For your Q2: 3CX PRO has a TLS of up to 6 Hours, whereas ENT is only 5 min.

 

[SteveITS]

@Ralib Your DynDNS FQDN and 3CX FQDN should point to the same IP?

Check that your 3CX server is set to use a Dynamic address in its network settings, not static.

> Can an alternative DNS server be configured to improve DynDNS update handling (e.g., Google DNS 8.8.8.8,

I'm not sure I understand...you can set whatever DNS servers you want in your 3CX VM.

 

[Alphabetic]

Have you got your 3CX set to dynamic?