What GoDaddy does wrong:
https://www.godaddy.com/help/enable...dy-nameservers-as-secondary-nameservers-23911
GoDaddy says: "You must enable your master nameserver set to allow AXFR requests from IP ranges 50.63.22.0-50.63.22.255 and 208.109.132.0-208.109.132.255".
Most external dns providers do allow to enter just a few ip addresses in "axfr allow" setup, not 512 addresses... and there is no way to enter netblocks!
Ref: rfc2182 /"Selection and Operation of Secondary DNS Servers"/. It is teaching us: Secondary Server is an "authoritative server that obtains information about a zone from a Primary Server via a zone transfer mechanism. Sometimes known as a Slave Server." There is nothing showing that slave server(s) can operate from 512 different IPs, which thing GoDaddy is asking for.
Moreover, GoDaddy says: "For best performance, set your master to send NOTIFY messages to 97.74.112.1 and/or 97.74.112.2".
Ref: rfc1996 /"A Mechanism for Prompt Notification of Zone Changes (DNS NOTIFY)/. It is teaching us: "The DNS NOTIFY transaction allows master servers to inform slave servers when the zone has changed". Nowhere it says that master dns should notify servers that are NOT listed as secondary ones, which is exactly what GoDaddy is asking to configure.
I have experienced all this in real life. My second DNS provider was of not help:
"I am sorry, I have tried to find any Godaddy information on what to do if only IP addresses can be entered as slave nameservers and have had no luck.. additionally i cannot find any information on them requiring Notify's to be sent to different IP addresses then what have been set as the slave nameservers. I do suggest you contact Godaddy support as the domain holder for their clarifications on this."
Similarly, GoDaddy support could not help. So, I am no more using GoDaddy premium DNS in this mode (which they implemented ~ Dec., 2020)
For the reasons of fairness, I should add that GoDaddy premium DNS, if used alone (without extra 3rd party DNS involved) is stable and working OK. No issues at all. No dowtimes /like with Dynadot
( /. Moreover, you can add other DNS servers/services if GoDaddy is used as primary - in this case, there would be no setup/compatibility issues. The last but not the least, GoDaddy Premium DNS also works for domains which are not registered with GoDaddy.